Background: Nephron-sparing surgery (NSS) is currently the recommended treatment modality for selected renal tumors. The prognostic significance of positive surgical margin (PSM) and surgical margin width (SMW) after NSS is controversial. Aim: To evaluate the effect of PSM and SMW on cancer-specific survival (CSS) in patients who underwent NSS. Materials and Methods: The pathological samples of 142 patients who underwent NSS were reviewed. Patients were divided into two groups with PSM and negative surgical margin (NSM), and after that those with PSM were divided into two groups according to SMW as those with 0.1-2 mm and those >2 mm. CSS was calculated using Kaplan-Meier method. Cox regression analysis was used to adjust the clinicopathologic variables. A P value < 0.05 was considered statistically significant. Results: Local recurrence rate and distant metastasis rate were higher in patients with PSMs than those with NSMs (P = 0.018 and P = 0.039, respectively). However, there was no significant difference between the two groups in terms of CSS. In the group with SMW 0.1-2 mm, the tumor diameter was longer (P = 0.018), enucleation number was higher (P = 0.026), and local recurrence was higher (P = 0.034) than the group with SMW > 2 mm. There was no significant difference between the two groups in terms of CSS. Conclusion: In patients who underwent NSS, PSMs and SMWs have a negative effect on local recurrence but have no significant effect on CSS.