In a group of viscose rayon workers exposed to carbon disulfide the systolic time intervals were calculated. They were determined from the simultaneous recording of an ECG, a phonocardiogram, and arterial pulse tracings. Results indicate a shortened left ventricular ejection time (lvet) and a prolonged isovolumetric contraction time (ICT), together with an increase in the ratio of ICT to LVET. These alterations, which occurred in the absence of any clinical signs or symptoms of heart disease, are interpreted as a consequence of an impaired left ventricular contractility, comparable to mild coronary dysfunction. Literature data support the hypothesis that the biochemical mechanisms involved in the effect of carbon disulfide on myocardial cells are (a) an interference with energy metabolism from the inadequate availability of thiamine and nicotinamide or a direct inhibition of cytochrome or (b) an interference with catecholamine metabolism and defective hormonal control of the energy utilization process. Impaired left ventricular function in rayon viscose workers exposed to carbon disulfide represents an early and highly sensitive sign of carbon disulfide intoxication, and the use of systolic time intervals as a noninvasive measure of myocardial performance may be a useful method for monitoring carbon disulfide exposed people.