The polymerase chain reaction was used to amplify herpes simplex virus (HSV) DNA from 79 clinical specimens from the female genital tract, and the results were compared with cell culture. Combining the polymerase chain reaction with visualization of amplified products using a direct gel analysis, HSV DNA was detected in 38 specimens, six of which were negative for virus by cell culture. Hybridization of the amplified products detected HSV in three other specimens. One specimen was positive for HSV by cell culture but negative for viral DNA by polymerase chain reaction. Specimen purification before the polymerase chain reaction improved the detection of viral DNA. Restriction endonuclease cleavage of amplified DNA seen by direct gel analysis, used to differentiate HSV-1 from HSV-2, was correct in each case. The analysis time using the polymerase chain reaction was 8-10 hours, making this technique potentially valuable in the clinical setting of parturition.