AbstractTumors from 30 patients with advanced gynecologic malignancies were evaluated for sensitivity or resistance to various chemotherapeutic agents by three laboratory assays: the subrenal capsule (SRC) assay, the stem cell clonogenic (SCC) assay, and a delayed [3H]TdR incorporation ([3H]TdR) assay. The tumors were tested against a standard battery of chemotherapeutic drugs; 39% of the tumors were sensitive to one or more of these agents in the SRC assay compared to only 24% in the [3H]TdR assay and 4% in the SCC assay. Eighteen of the patients had adequate follow‐up to correlate their clinical course to the assay predictions. In this study, the prospective predictive accuracy (sensitivity) of the SRC assay was 100% compared to 25% for the [3H]TdR assay and 0% for the SCC assay. The respective specificities were 63, 73, and 80%. The SRC assay appeared to predict clinical response for gynecologic malignancies more accurately than either the [3H]TdR or the SCC assa