Jamaica has the second highest number of acquired immunodeficiency syndrome (AIDS) cases and deaths in the Caribbean and a significant number of human immunodeficiency virus (HIV) infected individuals have a concomitant sexually transmitted infection (STI). The study determined the prevalence of non-ulcerative and ulcerative STIs and their association with sexual risky behaviour in a sample of HIV seropositive men and women. This study was conducted at the Comprehensive Health Centre in Jamaica, a sexually transmitted infection referral centre. The sample comprised 138 men and 132 women age 15-49 years, of average 29.5 years. The study was retrospective, from 2000 to 2002, and sample collection was randomized. The sexual behaviours of the subjects were assessed from the case records. In the 270 HIV diagnosed cases examined, the prevalence of STIs was 51.1% in men and 48.9% in women, with 85.4% having one or more STIs with an average of four STIs per patient. There was a total occurrence of 744 STIs with non-gonococcal urethritis (19.4%), gonorrhoea (17.2%), candidiasis (13.4%), trichomonas (12.4%), genital ulcer (10.4%) and syphilis (7.3%) the most common in HIV infected men and women. The presence of STI was associated with continued practice of risky sexual behaviour. The age group most implicated was the 30-34 year old, and 73.1% of the HIV infected patients had multiple sexual partners with only 16.4% reporting frequent condom use. The study demonstrates that there is a high prevalence of non-ulcerative and to a lesser extent ulcerative STIs in HIV infected patients in Jamaica. There are significant associations between STIs and continued high risk sexual practices in HIV infected men and women. The findings support the need for implementation of effective diagnosis and treatment strategies coupled with education about safe-sex practices in HIV prevention and STI control programmes.