A group of 9 patients in chronic hemodialysis was intensively studied for a year. The main findings were that the patients were content, functioned well in everyday life, and were nearly free of psychiatric symptoms. Uniform defenses--denial, displacement, isolation, reaction formation, and projection--were found in all patients, irrespective of varied backgrounds. These defenses, while adaptive in one sense, led to marked ego restriction. The hypothesis was advanced that the main stress of chronic hemodialysis was the dependency on the machines and the staff, and the aggression resulting from this dependency. Some of the clinical manifestations also suggested brain dysfunction. Psychological tests and EEG study furnished additional proof.