Since 1982, chemosensitivity studies have been conducted in our laboratory with 181 tumour samples from 132 woman patients suffering from carcinoma of the ovaries, using the colony test and capillary assays. Colonisation rates were 67% and assay rates between 60 and 47%; in 36 cases the in vitro result was compared with the course of the disease observed in vivo. Whereas in 11 of 12 patients it was possible to correctly assess chemoresistance (in vitro growth inhibition less than or equal to 49%) pretherapeutically, chemosensitivity (growth inhibition greater than or equal to 50%) proved more difficult to confirm, 15 predictions being true and 9 false. To assess the prognostic significance of the test results, survival curves were calculated from the data of 33 patients. With a p-value of 0.49, the courses of disease of "in vitro resistant" and "in vitro sensitive" patients differed only slightly from one another. We can conclude from our experiments, that an important indication for performing the colony test in ovarian carcinoma should always be assumed in patients with a poor prognosis, e.g. in women having a large postoperative residual tumour. If, in such cases, the possibility of chemosensitivity testing via the colony test is considered, this examination may offer the chance of sparing the patient additional strain due to the side effects of a treatment with cytostatics if the latter is most likely to be of no significant use.