The aim of this study was to examine the effects of increased carbon monoxide concentrations in the air of car cabin on the health status of exposed drivers and the occurrence of traffic accidents. Exposed group was comprised of 250 drivers professionally exposed to increased carbon monoxide concentrations in the car cabins. Control group was comprised of 120 professional drivers who were not exposed to increased concentrations of carbon monoxide in the air of the car cabins. Average carbon monoxide concentration in the air of the car cabins of the drivers from exposed group was 71.2 +/- 8.1 ppm, which was significantly higher compared to the controls (5.4 +/- 1.2 ppm). The drivers from the exposed group more frequently suffered from headaches, irritability, vertigo and palpitation than the drivers from the control group. The prevalence of diabetes mellitus, arrhythmia, atherosclerotic peripheral artery diseases and coronary heart diseases was more frequent in the exposed than in the control group. Drivers from the exposed had longer reaction time on acoustic and visual stimulation compared to the control group. The examined drivers statistically caused more traffic accidents than the drivers from the control group.