The comparison of the results obtained by the gas-chromatographic vapor-phase analysis and by the bacteriological analysis of exudate samples, taken from patients with intraperitoneal and intrapleural infections, has demonstrated high reliability of the chromatographic method. Despite the presence of some discrepancies between the results of the vapor-phase analysis and the bacteriological analysis due to the difficulties of the microbiological isolation of anaerobes and the specific features of their metabolism, the diagnostic value of the gas-chromatographic method has been confirmed.