To evaluate risk factors for coronary heart disease and factors which can influence the course of acute myocardial infarction in workers exposed to C 5 2 we performed a cross-sectional study of 247 workers in the viscose industry The control group of 222 men from the same plant was comparable for age, social status and physical work The C 5 2 exposure determined by personal air sampling ranged from < 0 2 ppm to 65 7 ppm (median: 4 0 ppm) and the duration of exposure ranged from 4 to 220 (median: 66) months Using a multiple linear regression model we found neither higher blood pressure at rest or after exercise, nor hyperlipoproteinaemia in a higher degree, nor lower high-density lipoprotein (HDL) or lower apolipoprotein A-I levels, nor higher blood glucose values, nor indicators of direct cardiotoxic effects or signs of disturbances in blood coagulation in the exposed group in comparison to controls Regarding the influence of chronic exposure on the investigated parameters, we found an inverse correlation of the cumulative exposure (mean C 5 2 exposure in the department multiplied by the duration of work in this department) with the HDL concentration The HDL levels correlated with the duration but not with the intensity of exposure In the same way the apolipoprotein A-I levels showed a negative association with the duration of