Plasma lipids, lipoproteins, fibrinogen and fibrinolytic activity (FA) were measured in 202 consecutive patients undergoing coronary angiography. Twenty-one patients, 13 men and 8 women with a mean age of 52.8 years and 56.7 years respectively, were found to be angiographically free of coronary artery disease (CAD) and served as the principal control group. Since this group contained a disproportionate number of subjects with risk factors such as family history, hypertension and smoking, a second control group of clinically healthy subjects selected for age was also tested. Their laboratory results were not used in the statistical calculations. The group with angiographic CAD consisted of 130 men (mean age 57.6 years) and 51 women (mean age 61.5 years). Abnormal angiograms were graded according to the number of major vessels with more than 50% stenosis involved. The laboratory variables which were significantly (p less than .01-.001) associated with the presence of CAD were: High density lipoprotein (HDL) when determined by polyacrylamide gel electrophoresis (PAGE) and expressed as a percentage of total lipoproteins rather than concentration, presence of Intermediate Density Lipoprotein (IDL), percent of Very Low Density Lipoprotein (VLDL), fibrinogen concentration and FA. The HDL2 subfraction was significantly inversely correlated only in women. The total plasma cholesterol was normal and virtually identical in both groups. Within the CAD group, only two of the laboratory results were significantly correlated with the extent of disease. By univariate analysis, the FA showed the closest association with the score for severity of CAD (p less than .001) followed by the presence of IDL (p less than .01). In conclusion, lipoprotein analysis by a method which measures not only HDL, but also LDL, VLDL and IDL, together with the determination of fibrinogen and FA provides information useful in the identification of individuals at risk for CAD.