Objective: Diabetic nephropathy is a serious complication of type 1 diabetes which involves one third of the patients. The aim of this study was to estimate the frequency of microalbuminuria in type 1 diabetic patients visited in Pediatric Endocrine Clinic in Hamedan, west province of Iran, in 2007.Methods: Diabetic patients visited in Pediatric Diabetes Clinic were enrolled in the study. Variable data such as age, sex, duration of the disease, stage of puberty, dose of insulin/kg/day, and blood pressure of the patients were obtained according to history and physical examination. 24h urine samples were collected for protein, creatinine, and microalbumine. Data analysis was assessed using independent t-test and chi-square test.Findings: One-hundred five patients (56 females and 49 males) with a mean age of 13.3±5.5 years were evaluated. Fifteen (14.3%) cases had microalbuminuria. Mean age in microalbuminuric group was 16.2±2.8, and in non-microalbuminuric group was 12.7±5.6 years (P=0.024). Mean duration of diabetes was 9.1±3.2 yr in microalbuminuric and 4.5± 3.9 in non-microalbuminuric group. There was a significant correlation between duration of diabetes and microalbuminuria (P<0.001). Blood pressure was normal in 95.5% of the patients while in patients with microalbuminuria 73.3% had hypertension (P<0.001). Frequency of microalbuminuria was higher in patients taking lower doses of insulin corrected to their body weight (P=0.008).Conclusion: Frequency of microalbuminuria was significant, so regular screening is highly recommended for early detection and timely treatment of diabetic nephropathy in order to prevent progression to end stage renal disease.