Five cases of scintigraphic imaging of haemostatic and thromboembolic processes after injection of autologous 111In-labelled platelets are presented. The site of a liver puncture, atherosclerotic plaques in the abdominal aorta, deep vein thrombi, pulmonary embolism and the tip of an indwelling venous catheter could be visualized. Activity measurements corresponding to atherosclerotic plaques suggest that an increased sensitivity of this method may be achieved by extending the investigation period to 4-5 days after injection of 111In platelets.