99mTc pyrophosphate was employed in the study of patients with hypertrophic pulmonary osteoarthropathy. Several facts emerge when comparing the radionuclide, radiographic and clinical findings. Radionuclide imaging reveals the presence and extent of subperiosteal activity with greater clarity than does radiography. Synovitis associated with the syndrome is readily disclosed, and the regression of the skeletal manifestions following excision of the pulmonary lesion can be documented.