The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. [...] Funding The Unified Budget, Results and Accountability Framework of the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the U. S. President’s Emergency Plan for AIDS Relief (PEPFAR) provided the funding to support this work, including the systematic reviews of evidence, evidence compilation, convening of the expert meeting, and development, editing, and printing of the guidelines. [...] People in prisons and other closed settings are included in these guidelines also because of the often high levels of incarceration of the other groups and the increased risk behaviours and lack of HIV services in these settings. [...] These guidelines aim to: provide a comprehensive package of evidence-based HIV-related recommendations for all key populations; increase awareness of the needs of and issues important to key populations; improve access, coverage and uptake of effective and acceptable services; and catalyze greater national and global commitment to adequate funding and services. [...] The systematic reviews and GRADE (Grading of Recommendations, Assessment, Development and Evaluation) tables for new recommendations appear in full in Web Annexes 1 and 2. 1.6 Goal and objectives These guidelines seek to provide consolidated guidance to inform the development and implementation of HIV policies, programmes and services for key populations.