Serum levels of TAG 72 were measured in 726 serum samples from patients with benign and malignant gynaecological conditions in order to evaluate the clinical usefulness of TAG 72 alone or in combination with other tumour markers. Sixty-six per cent of patients with ovarian cancer showed abnormal concentrations of TAG 72 antigen. A good correlation was also found between serial TAG 72 values and the clinical course of disease during chemotherapy and follow-up. In cervical and endometrial cancer abnormal TAG 72 values occurred in 23% and 14% of cases, while none of the patients with breast cancer had abnormal TAG 72 levels. Among patients with benign disease only one out of 12 patients (8%) with benign ovarian tumours and one of 15 patients with uterine fibromyomatosis (7%) showed high TAG 72 serum levels. However, the determination of TAG 72 did not increase the sensitivity of CA 125 and squamous cell carcinoma antigen (SCC), in ovarian and cervical cancer, respectively. The systemic administration of recombinant interferon alpha-2b to 15 patients with ovarian cancer and different basal levels of TAG 72 did not increase serum levels of the antigen.