SCHEDULE 13G Amendment No. 0 21VIANET GROUP INC Class A Ordinary Shares Cusip #90138A921 Check the appropriate box to designate the rule pursuant to which this Schedule is filed: [x] Rule 13d-1(b) [ ] Rule 13d-1(c) [ ] Rule 13d-1(d) Cusip #90138A921 Item 1: Reporting Person - FIL Limited Item 2: (a) [ ] (b) [ ] Item 4: Bermuda Item 5: 17,610,084 Item 6: 0 Item 7: 17,743,884 Item 8: 0 Item 9: 17,743,884 Item 11: 5.147% Item 12: FI Cusip #90138A921 Item 1: Reporting Person - Pandanus Partners, L.P. Item 2: (a) [ ] (b) [ ] Item 4: Delaware Item 5: 0 Item 6: 0 Item 7: 17,743,884 Item 8: 0 Item 9: 17,743,884 Item 11: 5.147% Item 12: PN Cusip #90138A921 Item 1: Reporting Person - Pandanus Associates, Inc. Item 2: (a) [ ] (b) [ ] Item 4: Delaware Item 5: 0 Item 6: 0 Item 7: 17,743,884 Item 8: 0 Item 9: 17,743,884 Item 11: 5.147% Item 12: CO Item 1(a). Name of Issuer: 21VIANET GROUP INC Item 1(b). Address of Issuer's Principal Executive Offices: M5, 1 Jiuxianqiao East Rd Chaoyang District Beijing, F4 100016 China Item 2(a). Name of Person Filing: FIL Limited Item 2(b). Address or Principal Business Office or, if None, Residence: Pembroke Hall, 42 Crow Lane, Hamilton, Bermuda, HM19 Item 2(c). Citizenship: Not applicable Item 2(d). Title of Class of Securities: Class A Ordinary Shares Item 2(e). CUSIP Number: 90138A921 Item 3. This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) or (c) and the person filing, FIL Limited, is a non-U.S. institution in accordance with Section 240.13d-1(b)(1)(ii)(J). (Note: See Exhibit A). Item 4. Ownership (a) Amount Beneficially Owned: 17,743,884 (b) Percent of Class: 5.147% (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: 17,610,084 (ii) shared power to vote or to direct the vote: 0 (iii) sole power to dispose or to direct the disposition of: 17,743,884 (iv) shared power to dispose or to direct the disposition of: 0 Item 5. Ownership of Five Percent or Less of a Class. Not applicable. Item 6. Ownership of More than Five Percent on Behalf of Another Person. Not applicable. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company. See attached Exhibit A. Item 8. Identification and Classification of Members of the Group. Not applicable. Item 9. Notice of Dissolution of Group. Not applicable. Item 10. Certifications. By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. By signing below I certify that, to the best of my knowledge and belief, the foreign regulatory scheme applicable to FIL Limited and its various non-U.S. investment management subsidiaries included on this Schedule 13G is substantially comparable to the regulatory scheme applicable to the functionally equivalent U.S. institutions. I also undertake to furnish to the Commission staff, upon request, information that would otherwise be disclosed in a Schedule 13D. Signature After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. June 9, 2014 Date /s/ Scott C. Goebel Signature Scott C. Goebel Duly authorized under Power of Attorney effective as of May 5, 2014, by and on behalf of FIL Limited and its direct and indirect subsidiaries. Exhibit A Pursuant to the instructions in Item 7 of Schedule 13G, the following table lists the identity and Item 3 classification, if applicable, of each relevant entity that beneficially owns shares of the security class being reported on this Schedule 13G. Entity ITEM 3 Classification FIL PENSION MANAGEMENT FI FIL INVESTMENTS INTERNATIONAL FI FIL INVESTMENT MANAGEMENT (HONG KONG) LIMITED * FI FIL INVESTMENT MANAGEMENT (SINGAPORE) LIMITED FI * Entity beneficially owns 5% or greater of the outstanding shares of the security class being reported on this Schedule 13G. Pandanus Partners L.P. ("Pandanus") owns shares of FIL Limited ("FIL") voting stock. While the percentage of total voting power represented by these shares of FIL voting stock may fluctuate as a result of changes in the total number of shares of FIL voting stock outstanding from time to time, it normally represents more than 25% and less than 50% of the total votes which may be cast by all holders of FIL voting stock. Pandanus Associates, Inc. ("PAI") acts as general partner of Pandanus. Pandanus is owned by trusts for the benefit of members of the family of Edward C. Johnson 3d but disclaims that any such member is a beneficial owner of the securities reported on this Schedule 13G. This filing reflects the securities beneficially owned, or that may be deemed to be beneficially owned, by FIL, certain of its subsidiaries and affiliates, and other companies (collectively, the "FIL Reporters"). This filing does not reflect securities, if any, beneficially owned by certain other companies whose beneficial ownership of securities is disaggregated from that of the FIL Reporters in accordance with Securities and Exchange Commission Release No. 34-39538 (January 12, 1998). RULE 13d-1(k)(1) AGREEMENT The undersigned persons, on June 9, 2014, agree and consent to the joint filing on their behalf of this Schedule 13G in connection with their beneficial ownership of the Class A Ordinary Shares of 21VIANET GROUP INC at May 30, 2014. FIL Limited By /s/ Scott C. Goebel Scott C. Goebel Duly authorized under Power of Attorney effective as of May 5, 2014, by and on behalf of FIL Limited and its direct and indirect subsidiaries Pandanus Partners, L.P By /s/ Scott C. Goebel Scott C. Goebel Duly authorized under Power of Attorney effective as of May 2, 2014, by Pandanus Associates, Inc. on behalf of Pandanus Partners, L.P. Pandanus Associates, Inc. By /s/ Scott C. Goebel Scott C. Goebel Duly authorized under Power of Attorney effective as of May 2, 2014, by and on behalf of Pandanus Associates, Inc. Page of