Trichomoniasis remains an extremely common infection despite the fact that rates of other treatable sexually transmitted diseases are declining. Newer diagnostic techniques such as polymerase chain reaction (PCR) are documenting higher rates of infection in heterosexual men than have been previously found with culture. Although data on the association of vaginal trichomoniasis with preterm birth are controversial, the association of trichomoniasis with HIV acquisition seems clear. Despite being a readily diagnosed and treated STD, trichomoniasis is not a reportable infection and control of the infection has received relatively little emphasis from public health STD control programmes. More recently, however, appreciation of high rates of disease and of associations of trichomoniasis in women with adverse outcomes of pregnancy and increased risk for HIV infection suggest a need for increased control efforts.