Background: The etiology of diabetic nephropathy depends partly on genetic factors. Elevated systemic and intraglomerular blood pressure and glomerular filtration rate, partly regulated by the renin-angiotensin system, increase the risk of diabetic nephropathy. Methods: The present case-control study investigated the association of the rs5186 polymorphism, in the angiotensin II type 1 receptor gene (AGTR1), with diabetic nephropathy. The study included 3561 patients with type 1 diabetes from Denmark, Finland, France and Sweden. Microalbuminuria was defined as albumin excretion rate (AER) ≥ 20 to < 200 μg/min or albumin concentration ≥30 to <300 mg/l (n = 707), macroalbuminuria was defined as AER ≥ 200 μg/min or ≥ 300 mg/l (n = 1546), and patients with renal replacement therapy were also included in this group. The controls had > 15 years diabetes duration, AER < 20 μg/min or < 30 mg/l, and no antihypertensive treatment (n = 1308). Results: AA genotype of the rs5186 polymorphism significantly increased the risk of diabetic nephropathy in male patients, OR = 1.27 (95% CI = 1.02-1.58), P = 0.03, adjusted for age at diabetes onset, HbA1c, diabetes duration, smoking and country of origin. Among the women, there were no significant associations between rs5186 and diabetic nephropathy, OR = 0.89 (0.71-1.11), P = 0.30. Conclusion: We conclude that the AGTR1 gene may be associated with increased risk of diabetic nephropathy in men with type 1 diabetes.