Microalbuminuria has a cumulative incidence of > 30% in persons by 25 y duration of insulin-dependent diabetes mellitus (IDDM) and is a strong predictor of renal disease and mortality. Although improved glycemic control, maintenance of normal blood pressure, and use of angiotensin-converting enzyme inhibitors are important strategies to avoid developing microalbuminuria, dietary macronutrient intake may also play a role. A cross-sectional population-based study of Tasmanian adults with IDDM and no previous diagnosis of microalbuminuria was conducted by measuring usual dietary macronutrient intake with a food-frequency questionnaire and defining microalbuminuria as an average urinary albumin excretion rate between 20 and 200 micrograms albumin/min in at least two of three timed overnight urine collections. After sex, age, duration of diabetes, daily number of insulin injections, body mass index, glycated hemoglobin, serum high-density-lipoprotein cholesterol, frequency of exercise, and smoking status were adjusted for, the adjusted odds ratio for microalbuminuria for the highest quintile of energy-adjusted usual saturated fat intake compared with the lowest quintile was 4.9 (95% CI: 1.2, 20.0; P = 0.03). The adjusted odds ratio for microalbuminuria for the highest quintile of energy-adjusted usual protein intake compared with the lowest quintile was 0.10 (95% CI: 0.02, 0.56; P = 0.01). There was no significant association between microalbuminuria and energy-adjusted carbohydrate intake, energy-adjusted monounsaturated fat intake, or energy-adjusted polyunsaturated fat intake.