Abstract: Introduction: Despite the multisystem nature of Behcet’s disease (BD), renal involvement is rare in this disease. The aim of this study was to find the prevalence and characteristics of urine abnormalities and renal involvement of BD in Iran. Patients & methods: In a cohort of 4704 patients with BD, urinalysis was performed to screen patients with urine abnormalities. Different manifestations of the disease, including 100 clinical and paraclinical parameters, were determined in these patients and compared with the remaining group of patients (with normal urinalysis) by chi square test and Fisher exact test. A confidence interval at 95% (CI) was calculated for each item. Results: Urinalysis had been performed at least once in the course of the disease in 4386 patients. Abnormal urine was found in 475 (10.8%, CI=0.9) patients. Proteinuria was seen in 101 patients (2.3%, CI:0.4). It was related to joint (p=0.00001), GI (p<0.0008), and large vessel involvement (p<0.02), high ESR (p<0.00003), and false positive VDRL (p=0.000001). Hematuria was seen in 222 cases (5.1%, CI:0.6). It was related to genital aphthosis (p<0.02), retinitis (p<0.03), joint (p<0.0002), GI (p<0.004), and CNS (p<0.02) involvement, high ESR and positive VDRL (p<0.02). Renal casts was seen in 13 cases (0.3%, CI:0.2). It was related to arthralgia (p<0.007) and high ESR (p<0.02). Kidney biopsy was performed only in 14 cases that showed mesangial glomerulonephritis (GN) in 3, focal and diffuse proliferative GN each in 5, and amyloidosis in 2 cases. Conclusion: Renal involvement is rare in BD patients, although transiant urine abnormalities are not uncommon. These abnormalities are related to joint and GI involvement, high ESR, and false positive VDRL. Amyloidosis is rare in Iranian patients.