The demand for high-quality ventilation imaging of the lungs has resulted in the advent of Technegas, which has proven its superiority to the more conventional agents in a number of clinical trials. Images of similar diagnostic quality have been difficult to obtain in patients who are uncooperative, intubated or very young. With this problem as the impetus, a ventilatory assistance device (VAD) was designed to exploit the superior imaging qualities of Technegas. The Technegas generator was interposed between the patient and the VAD, allowing the controlled movement of Technegas into the patient from the generator. Utilizing this device, the problems of increased dead space, turbulent gas flow and possible contamination were circumvented. Twenty patients, comprising nine children and eleven adults, were studied for various indications including assessment of pulmonary parenchymal disease, suspected pulmonary embolism and the lung clearance of modified Technegas. In all cases, images of diagnostic quality were obtained with ease, facilitating relevant clinical decision making. We conclude from this preliminary appraisal that the VAD is a simple, safe addition to the Technegas generator for imaging a group of patients in whom images of diagnostic quality have traditionally proven difficult to obtain.