A patient with malignant mesothelioma experienced tumor recurrence 3 months after pleuropneumonectomy. Samples of the tumor were transplanted into nude mice to assess chemosensitivity. There was close concordance between the results in xenografts and the clinical outcome in this patient. Both mitomycin and to a lesser extent cisplatin were effective as single agents against the nude mouse xenografts, and the combination of these two drugs produced a complete response both in the patient and in the xenografts. The patient survived 18 months from onset of chemotherapy and 24 months from diagnosis. The duration of clinical complete response to chemotherapy was 14 months, despite the fact that mitomycin, the most effective agent against the xenografts, was discontinued after only two cycles because the patient developed pulmonary toxicity. This direct patient-xenograft correlation further validates the usefulness of the nude mouse model in the search for effective therapies for malignant mesothelioma, a tumor characterized by frequent refractoriness to most available agents.