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United Nations Office of Internal Oversight Services (UN OIOS)
Headquarter: New York, United States
United Nations System
New York, United States


The United Nations Office of Internal Oversight Services (OIOS) is the internal oversight body of the United Nations. Established in 1994 by the General Assembly, the Office assists the Secretary-General in fulfilling his oversight responsibilities in respect of the resources and staff of the Organization through the provision of audit, investigation, inspection and evaluation services.

To carry-out its work, the Office is organized into the following functional units:

  1. Internal Audit Division - audit assesses the adequacy and effectiveness of internal controls for the purpose of improving the Organization’s risk management, control and governance processes.
  2. Inspection and Evaluation Division - evaluation assesses the relevance, efficiency and effectiveness (including impact) of the Organization’s programmes in relation to their objectives and mandates. 
  3. Investigations Division - investigation establishes facts related to reports of possible misconduct to guide the Secretary-General on jurisdictional or disciplinary action to be taken.
  4. Leadership - the Office is headed by the Under-Secretary-General for Internal Oversight Services, Ms. Heidi Mendoza, who is appointed by the Secretary-General, following consultations with Member States, and approved by the General Assembly for one five-year term without possibility of renewal. 
  5. Coordination and Cooperation - OIOS covers all United Nations activities under the Secretary-General's authority, including: the UN Secretariat in New York, Geneva, Nairobi and Vienna, five regional commissions, peacekeeping missions and humanitarian operations; assistance to Funds and Programmes administered separately under the authority of the Secretary-General (including UNHCR, UNEP, UN HABITAT, and OHCHR), and other entities that have requested OIOS services such as UNCCD and UNFCCC.
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