Four patients with stage IA-IIIC dysgerminomas were found to have preoperative elevations of serum lactic dehydrogenase (LDH) 1.8-51.5 times that of the upper limits of normal control values, in association with minor elevations of liver function tests (alkaline phosphatase, serum glutamic oxaloacetic transaminase, and serum glutamic pyruvic transaminase) up to 2.5 times normal control limits. Recognition of the association between this serum enzyme profile and dysgerminoma resulted in proper intraoperative staging and prompt initiation of chemotherapy in two patients. Failure to recognize the significance of the serum enzyme profile resulted in inadequate intraoperative staging and reoperation in one of the remaining patients. Serum LDH levels correlated with tumor size and stage of disease. Maximum tumor diameters in this series varied from 15-20 cm. A normal LDH level was present in an intraoperative serum sample obtained from a stage IA patient whose maximum tumor diameter was 8 cm. Selective elevation of LDH-1 and LDH-2 isoenzymes may provide additional evidence suggesting the presence of a dysgerminoma.