The levels of cholesterol (C) and triglycerides (TG) were studied by a standard biochemical assays and the amount of C and TG was examined by a fluorescence assay in 55 patients with complicated (n=32) and uncomplicated (n=23) acute myocardial infarction (AMI) and in 25 apparently healthy donors. The content of C did not differ significantly in the study groups. As compared with the controls, the patients with complicated AMI had lower values of C + TG (p < 0.01) and TG (p < 0.001). In the patients with uncomplicated AMI, these indices were also lower than those in the control, but not significantly. The patients with complicated AMI were found to have insignificantly lower levels of TG and C + TG than those with uncomplicated AMI. The lower level of TG seems to be responsible for the decreased C + TG amount detectable in AMI by a fluorescence assay.