The chronic female disease endometriosis causes debilitating pain and lowered fertility. The aetiology is unknown, but indications of an infectious agent are present. This study investigates the possible involvement of a pathogenic virus in endometriosis patients and controls. DNA was purified from biopsies and subjected to highly sensitive PCR tests detecting human papillomavirus (HPV) types, the herpes family viruses HSV-1 and -2, CMV, and EBV, and the polyomaviruses SV40, JCV, BKV, KIV, WUV, and MCV. The prevalence of pathogenic DNA viruses in the human endometrium was generally low (0-10%). The virus prevalence was found to vary slightly when comparing the endometrium of healthy women and women with endometriosis. However, these were not significant differences, and no viruses were identified in endometriotic lesions. These results do not point towards any evidence that endometriosis is caused by these viruses.