Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Delayed haemorrhage has not been well defined in the literature, clinical presentation has not been well described and treatment algorithms are lacking. From our experience we have shown that patients presenting with delayed bleeding after laparoscopic partial nephrectomy will need definitive rather than conservative treatment and angiographic findings demonstrate definitive lesions in all cases. Potential benefits include faster diagnosis and initiation of definitive treatment (angiography with embolization), avoiding repeat computed tomography imaging as it adds little in such patients and reducing need for prolonged hospitalization. Objectives: To determine the frequency of delayed postoperative haemorrhage requiring selective angioembolization (SAE) after laparoscopic partial nephrectomy (LPN). To describe the clinical presentation and characterize the angiographic findings encountered in this setting. Patients and methods: Prospective data from 640 LPNs performed between August 1993 and May 2009 were retrospectively analyzed, from which patients with delayed postoperative haemorrhage (defined as 'gross haematuria ≥7 days postoperatively that persists for more than 24 h') and requiring SAE were identified. Clinicopathological, preoperative and perioperative factors were reviewed. Selective catheterization and angiography of the renal artery was performed for persistent gross haematuria and for haemodynamic instability associated with a significant drop in haematocrit level. Arteries feeding the bleeding site were identified and embolized with endovascular coils. Results: Patients presented with delayed haemorrhage between 7 and 30 days after surgery. SAE was required in 13 patients (2%) for delayed postoperative bleeding. Of the 640 LPNs, 68 (10.6%) were performed without hilar occlusion ('off-clamp') of whom one (1.5%) had a delayed haemorrhage, which was successfully embolized. For patients with and without delayed haemorrhage after LPN, the mean tumour size was 2.7 cm and 3.3 cm (P= 0.31), the mean warm ischaemia time was 28.2 min and 14.3 min (P < 0.001), and the mean estimated blood loss 403.8 mL and 308.2 mL (P= 0.26), respectively. Percutaneous angiography showed renal artery pseudoaneurysm in 10 patients and arterial contrast extravasation in three patients, two of whom also had an arteriovenous fistula. Following embolization, creatinine levels remained stable in all patients. Conclusions: Clinically significant delayed postoperative bleeding after LPN occurs in a small percentage of patients. Angiography will accurately make the diagnosis of RAP or AVF and SAE is safe and effective procedure that allows for preservation of renal function. © 2010 BJU International.