The addition of chemotherapy to planned multiple modality treatment of patients with advanced head and neck squamous cell carcinomas may improve survival rates, but individual tumor response is unpredictable. An assay for determining tumor responsiveness to specific chemotherapeutic agents would facilitate treatment selection. This study used the subrenal capsule (SRC) assay to test responsiveness of squamous cell carcinoma to cisplatin. Tumor xenografts obtained from ten patients were implanted beneath the renal capsules of control and treatment mice. Tumor responsiveness was determined by using the paired Student's t-test to compare base-line and post-treatment measurements in the cisplatin-treated mice. Results indicated six of ten tumors were sensitive to cisplatin. In conclusion, tumor sensitivity to cisplatin and other drugs may be predictable with the SRC assay, but to be clinically useful, studies will be necessary to correlate assay results with responses observed in patients.