Nephron-sparing surgery (NSS) is a standard surgical treatment for small renal tumors. We report four patients (aged 35-79 years) with vascular complications within 6 days to 3 months after open NSS. Three patients developed acute symptoms, whereas one was asymptomatic. Computed tomography (CT) in the arterial and venous phase of contrast enhancement was performed for diagnosis, followed by angiography. CT demonstrated a perirenal hematoma in three and an arterial pseudoaneurysm in two cases. Unlike CT, digital subtraction angiography confirmed an arterial pseudoaneurysm in all cases and additionally found an arteriovenous fistula in three. In all cases, angiography-guided coil embolization successfully treated the vascular pathology, while preserving renal function. Clinicians should understand the diagnosis and management of this complication of NSS.