The effectiveness of ultrasound in the follow-up of tumor masses during chemotherapy was investigated over a period of 3 years in 74 patients with proven ovarian cancer. 47 had stage 3 disease, and 22 showed recurrence. Two or more examinations were performed in 65% of the patient. A correlation with surgical second look showed a correct diagnosis in 67.6%. The results of ultrasonographic follow-up when compared with clinical monitoring showed 75% concordant judgments on the therapeutical tumor response. The validity and limitations of this technique are discussed.