The aim of the study was to evaluate the usefulness of serial lung perfusion scintigraphy prospectively using single-photon emission computed tomographic image (SPECT) in screening for pulmonary embolism (PE) after elective surgery for gastrointestinal malignancy. PE was examined pre- and postoperatively with SPECT. Diagnosis of PE was based on segmental perfusion defect visualization in at least two of three planes on a SPECT image compared with preoperative SPECT images. Final diagnosis was determined by detection of embolus with multidetector helical CT (MDCT). No perioperative anticoagulant was used. Thirty-four patients were enrolled. One patient was excluded because of thrombophilia. In preoperative scans, nonsegmental defects were detected in 11 and a segmental defect in 1 patient, who was then diagnosed as PE preoperatively. Among 21 patients with normal preoperative SPECT, 2 had nonsegmental and 5 had segmental defects postoperatively. Among 11 patients with nonsegmental preoperative SPECT, 7 had nonsegmental and 4 had segmental defects postoperatively. Postoperative segmental defects were differentiated by their shape only and there was no need to compare pre- and postoperative SPECT. MDCT confirmed four patients with PE among nine with segmental defects postoperatively. Our results of screening for PE by visualization at least two planes of SPECT images suggest that postoperative SPECT scan is suitable for the diagnosis of postoperative PE.