The sinus rhythm resting heart rates of 138 schizophrenic patients were monitored electrocardiographically each for 30 min and were compared with those of 139 healthy controls. It was found that a signifìcant sinus tachycardia existed in the patients. Factors of chronologic age, sex and treatment by psychotropic drugs were non-significant. A subsample of 22 process schizophrenic patients was compared with 20 healthy controls, matched for age, monitored continuously for a minimum of 120 min and analyzed by autocorrelation on a minute-by-minute basis for cardiac rate variation. Ultradian rhythms of each group revealed that the periodicity of cardiac rate variation in schizophrenia was significantly longer than that in health. Treatment by psychotropic drugs in half of the patient sample did not appear to influence the cardiac rate variation. It is suggested that the bradycardia existing between pulses of tachycardia in schizophrenia may be responsible not only for the dysplastic perception of these patients, but also for their premature death from vascular causes