72 patients with hormone resistant, progressing prostatic cancer completed a self-administered questionnaire to assess subjective morbidity and quality of life before they were entered into a phase III trial of estramustine (34) vs. mitomycin (38). At least one post-treatment assessment was available in 43 patients. This considerable degree of non-compliance is explained by practical problems related to completion and collection of the questionnaires in these rapidly deteriorating patients. Doctors underestimated subjective morbidity (pain, decreased performance status, nausea) in 30-50% of the cases. Decreased functional status, fatigue and pain were identified as the most frequent major morbidities before study entry. In most patients, treatment did not reduce this morbidity. The routine application of self-administered quality of life questionnaires has considerable practical problems but yields clinically worthwhile information about subjective morbidity. Simple but relevant monitoring of subjective morbidity by the patient should be mandatory in cancer trials where palliation is a major endpoint.