To examine the influence of glucose intolerance in familial hypercholesterolemia (FH) on coronary heart disease (CHD), we measured serum and lipoprotein lipid levels in heterozygous FH patients with and without glucose intolerance. The patients with FH were classified as having normal (N), borderline (B) and diabetic (D) glucose tolerance by 50 g OGTT according to the criteria of the Japan Diabetic Society. Fasting blood glucose levels (mean) were 78 mg/100 ml (N, n = 8), 97 (B, n = 10) and 199 (D, n = 9) in females and 85 (N, n = 12), 93 (B, n = 21) and 185 (D, n = 15) in males, respectively. Prevalence of CHD was 50% (N), 56 (B) and 89 (D) in females and 58 (N), 67 (B) and 50 (D) in males, respectively. Serum cholesterol (Chol) and triglyceride (TG) levels (mean) were 351 mg/100 ml and 112 mg/100 ml (N), 323 and 102 (B), and 342 and 187 (D) in females and 356 and 93 (N), 338 and 121 (B), and 305 and 161 (D) in males, respectively. Serum Chol in D was significantly lower than in N in males (p less than 0.02). Serum TG in D was significantly higher than in N (p less than 0.05) in both males and females. Chol and TG of VLDL in D (n = 15) were significantly higher than in B (n = 19) (p less than 0.02 and p less than 0.05) and in N (n = 15) (p less than 0.05 and p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)