The seroprevalences of hepatitis B virus (HBV), hepatitis C virus (HCV), human T lymphotropic virus type-1 (HTLV-1) and syphyilis were determined in 129 HIV-1-infected patients using commercially prepared reagents. The seroprevalences were HCV, 0% (0/129); HBV, 37% (48/129); HTLV-1, 5% (6/129) and syphilis, 20% (26/129). Fifteen per cent (19/129) of the patients had active/chronic HBV infection. The seroprevalence of HBV was statistically significantly higher in HIV-1 infected men (24/49, 50% versus 17/80, 21%; p = 0.005), while the seroprevalence of syphilis was statistically significantly increased in HIV-1 infected patients in the over-40 age group (10/31, 32% versus 6/53, 11%; p = 0.05). These findings throw the spotlight on HBV infection and syphilis and suggest that these two sexually transmitted infections should be carefully surveyed in patients with HIV/AIDS in Jamaica. It is essential for management protocols in Jamaica to include screening for evidence of these co-infections.