Prompt diagnosis of a large pulmonary embolus is essential in order to initiate appropriate treatment early. We report a case of a large pulmonary embolus in which management was aided solely by noninvasive investigations. Transthoracic echocardiogram showed elevated right heart pressures which together with the patient symptoms suggested a major pulmonary embolus. Spiral computed tomography of the chest confirmed the diagnosis. The source of the embolus was shown by echodoppler. This case illustrates that a diagnosis of a major pulmonary embolus can be made using noninvasive techniques. Pulmonary angiography should be reserved for those rare cases in which diagnostic uncertainty remains rather than being used as a routine examination prior to consideration of therapeutic decision.