We have carried out a retrospective clinical investigation of 45 women in the first and second trimester of pregnancy aiming to demonstrate the role of genital HSV infection in the genesis of spontaneous abortion (miscarriage). Latent HSV infection was diagnosed using the microneutralization test; asymptomatic HSV vaginal or cervical shedding was diagnosed with indirect immunofluorescence and cytological-Papanicolau staining. The results showed that the highest incidence of latent HSV type 2 infection (64%) occurred in women who had one or more spontaneous abortions, whereas this type of infection was found in only 5% of pregnant women of the control group. The incidence of asymptomatic cervical HSV type 2 infection was also considerably higher in patients with a history of spontaneous abortions. Our results indicate a possible aetiological connection between HSV and spontaneous abortion.