OBJECTIVE: Our objective is to assess the safety of a surgical technique applied to the difficult left upper lobectomy. The inflowoutflow occlusion technique features: dividing the superior pulmonary vein first, then proximal control by clamping the main pulmonary artery (PA), and then distal control by clamping the inferior pulmonary vein. METHODS: A retrospective cohort study of a prospective database was carried out. Patients who underwent left upper lobectomy and required clamping of the vessels were compared to those that did not. RESULTS: Between January 1999 and March 2010,1796 lobectomies were performed and 360 (23%) of these were left upper lobectomies. Of these, 84 (23%) required the inflow-outflow occlusion technique. There were 70 (83%) men (median age 65 years). Fifty-one patients (61%) required resection of the PA and 33 did not. Heparin was not used in the last 17 patients. These 84 patients were compared to the remaining 276 patients who underwent standard left upper lobectomy. Although the median operative time was longer (150 vs 105 min, p < 0.001) and the median blood loss was greater (120 vs 87 ml, p = 0.03) for the inflow-outflow technique, there were no significant differences in hospital length of stay, morbidity, or mortality between the two groups. CONCLUSION: In our experience, clamping of the inferior pulmonary vein instead of the distal PA achieves safe distal vascular control. It affords greater PA mobility and assessment of the tumor and easier PA repair. This technique can be used even when PA resection is not required. © The Author 2011. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.