Objective: To investigate the attitudes of the main stakeholders towards the introduction of sex education in schools in Russia. Design: Qualitative semi-structured interview study. Setting: Altai Krai, Volgograd Oblast, Moscow, Russian Federation. Participants: One hundred and fifty-three interviews with Intersectoral HIV/AIDS Committee members, government officials responsible for HIV policies and interventions, non-governmental organisation and private-sector representatives. Main outcome measures: Perception of and attitudes towards the introduction of sex education in schools. Results: Ninety-one per cent of stakeholders welcomed the introduction of sex education in schools and emphasised its importance for a child's personal development, public health, sexually transmitted diseases and HIV/AIDS control, and pregnancy planning. The majority of respondents suggested providing different information for each age and grade. Despite the claimed support of interviewed policy-makers and main HIV stakeholders, there has been no action to introduce sex education. The majority of respondents were of the view that wider positive support through propaganda about health, sex and healthy lifestyle should be gained prior to introducing sex education in schools by addressing the stigma surrounding sexual issues. Conclusions: There was little opposition to the introduction of sex education in Russian schools expressed in our survey, but there are uncertainties regarding curriculum quality, teaching methods and the starting grade of teaching about sex, and there is a need to cover local sensitivities in the territories. These concerns could and should be addressed during curriculum design, development and programme implementation by the federal and local authorities. Wider involvement of educational specialists, peer-adults, health workers, celebrities and religious representatives in discussion of the curriculum could help prevent opposition to its implementation. Contribution to knowledge: Discussion of sex-related topics has been taboo in Russia and there has been little research into opinions on issues related to sex education. The contribution of this research is in gaining theoretical in-depth understanding of the attitudes of the interviewed stakeholders in Russia about the introduction of sex education in schools. (Contains 2 tables.)