Prior studies estimate HIV prevalence of 4% among injection drug users (IDUs), compared with 0.8% in the general population of Tijuana, Mexico. However, data on HIV prevalence and correlates among non-injecting drug users (NIDUs) are sparse. Individuals were recruited through street outreach for HIV testing and behavioural risk assessment interviews to estimate HIV prevalence and identify associated sexual risk behaviours among NIDUs in Tijuana. Descriptive statistics were used to characterise 'low-risk' NIDUs (drug users who were not commercial sex workers or men who have sex with men). Results showed that HIV prevalence was 3.7% among low-risk NIDUs. During the prior six months, 52% of NIDUs reported having >1 casual partner; 35% reported always using condoms with a casual partner; and 13% and 15%, respectively, reported giving or receiving something in exchange for sex. Women were significantly more likely than men to have unprotected sex with an IDU (p<0.01). CONCLUSIONS The finding that HIV prevalence among NIDUs was similar to that of IDUs suggests that HIV transmission has occurred outside of traditional core groups in Tijuana. Broad interventions including HIV testing, condom promotion and sexual risk reduction should be offered to all drug users in Tijuana.