Background: This study compared single-photon emission CT (SPECT) ventilation/perfusion (V/Q) scintigraphy with multislice CT pulmonary angiography (CTPA). Methods: In a prospective, observational study, 100 patients who were ≥ 50 years of age were recruited. Seventy-nine patients underwent both diagnostic 16-detector CTPA, and planar and SPECT V/Q scintigraphy. The agreement between the CTPA and the SPECT V/Q scintigraphy for the diagnosis of pulmonary embolism (PE) was calculated. The sensitivity and specificity of blinded SPECT scintigraphy reporting was calculated against a reference diagnosis made by a panel of respiratory physicians that was provided with CTPA and planar V/Q scintigraphy reports, clinical information, and 3-month follow-up data. Results: The observed percentage of agreement between SPECT V/Q scintigraphy and CTPA data for the diagnosis of PE was 95%. When calculated against the respiratory physicians’ reference diagnosis, SPECT V/Q scintigraphy had a sensitivity of 83% and a specificity of 98%. Conclusions: This study indicates that SPECT V/Q scintigraphy is a viable alternative to CTPA for the diagnosis of PE and has potential advantages in that it was feasible in more patients and had fewer contraindications; lower radiation dose; and, arguably, fewer nondiagnostic findings than CTPA. Abbreviations: CTPA = CT pulmonary angiography; PE = pulmonary embolism; PIOPED = Prospective Investigation of Pulmonary Embolism Diagnosis; SPECT = single-photon emission CT; V/Q = ventilation/perfusion.