Objective. It has been reported in recent studies that nephron-sparing surgery (NSS) is as effective as radical nephrectomy (RN) for pT1a and pT1b renal cell carcinoma (RCC). In order to decrease the rate of tumor recurrence, resection of a small amount of normal parenchyma surrounding the tumor is widely recommended. Although a 0.5-1.5-cm wide resection margin is recommended no agreement has been reached concerning the thickness of the surgical margin. In this study we tried to determine whether routine frozen-section biopsy from the surgical bed is mandatory during NSS for RCC. Material and methods. The study involved 19 renal units of 18 patients who underwent partial nephrectomy for solid renal tumors (<7 cm) at different centers in Ankara. Hypothermic ischemia was instituted after placing the kidney in an intestinal bag full of ice slush and cross-clamping the renal artery. In all cases an approximate to 1-cm margin of normal tissue was removed with the tumor. Then, intraoperatively, at least three frozen-section biopsies were taken from the surgical bed to determine the surgical margin. If the biopsy was positive, RN was performed. Results. All patients were staged as pT1a or pT1b according to the 2002 TNM classification. The average tumor size was 3.8 cm. In three cases we performed RN due to positive surgical margins. Surgical margins were negative in 16 tumors, with a mean negative margin size of 5 mm (range 2-11 mm). One patient died of a non-cancer-related cause. The mean distance to the renal capsule was 7 mm (range 1-11 mm). Seventeen patients were followed up for 18 months with no local or systemic recurrence. Conclusion. In some cases an approximate to 1-cm margin is not sufficient to ensure a negative margin and frozen-section biopsies must be taken from the tumor bed, even if it seems normal macroscopically.