Objective - Plasma concentrations of lipoprotein (a) [Lp(a)], an independent risk factor for atherosclerosis, were measured in 59 non-insulin-dependent diabetes mellitus (NIDDM) patients with and without vascular complications, and 21 non-diabetic healthy subjects. Results - The plasma log Lp(a) levels were found to be significantly increased in the NIDDM patients (1.40 ± 0.36) compared with the healthy subjects (1.02 ± 0.53; p < 0.05). Plasma Lp(a) levels in NIDDM patients with diabetic vascular complications (1.51 ± 0.27) were significantly higher than those of the NIDDM patients without diabetic vascular complications (1.23 ± 0.43) and healthy subjects (p < 0.05). There were significant correlations between plasma log Lp(a) levels and apolipoprotein B (apo B) in all NIDDM patients (r: 0.68, p < 0.05). No correlation was observed between Lp(a) levels and age, sex, duration of diabetes, fasting blood glucose, haemoglobin A1c, the mode of treatment, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and apolipoprotein AI levels in all patients. Conclusions - It was concluded that Lp(a) was a risk factor for angiopathy in NIDDM patients and the patients who have a high plasma Lp(a) concentration should be kept under strict glycaemic control.