We measured serum concentrations of apolipoproteins (apo A-I, A-II, B, C-II, C-III and E) in patients with thyroid disease (hyperthyroidism; n = 44, hypothyroidism; n = 15) and in normal subjects (n = 89). We found that apoA-II, B and C-III concentrations revealed significant difference among three groups of the normal (apoA-II; 31.4 +/- 4.9 mg/dl, apoB; 85.8 +/- 16.3 mg/dl, apoCIII; 7.45 +/- 2.99 mg/dl), hyperthyroidism (apoA-II; 29.8 +/- 5.4, apoB; 63.4 +/- 18.9, apoC-III; 6.28 +/- 2.45) and hypothyroidism (apoA-II; 27.5 +/- 5.3, apoB; 108.0 +/- 30.9, apoC-III; 9.43 +/- 2.74). Thyroid hormones showed clear negative correlation to apoB (r = 0.70, p < 0.001). Furthermore, apoC-III was also found to be negatively correlated with thyroid hormone concentrations (r = 0.47, p < 0.001).