The Sexual Risk Cognitions Questionnaire was designed to assess the type and frequency of cognitions associated with unsafe sex. It consists of 22 core items (SRCQ-22) with six subsections. Each subsection consists of 8-12 items designed for specific subgroups defined by gender, sexual orientation and HIV serostatus. Data on reliability and validity are presented based on a sample of 344 respondents in London. Reliability for all sections of the questionnaire was high but sample numbers were relatively small for some subsections. Validity for the SRCQ-22 was assessed in terms of its relationship with self-reported sexual behaviour among men who have sex with men who made up the largest proportion (70%) of the sample. The results indicate that the SRCQ-22 is a reliable measure for assessing cognitions related to HIV risk sexual behaviour in this population and supports the view that they are important determinants of safe and unsafe behaviour.