Five cases are reported of patients who developed a raised right hemidiaphragm while an indwelling central venous catheter was in situ. The patients were being treated with protracted venous infusions of chemotherapy for colorectal carcinoma. All five patients had a chest radiograph following insertion of the Hickman line which showed normal diaphragmatic positions. A mean of 93 days later (range 55-134 days) elevation of the right hemidiaphragm was noted in these patients on repeat chest radiographs. Two of the patients had a right phrenic nerve palsy demonstrated by magnetic stimulation of the nerve. The remaining three patients had paradoxical motion of the right hemidiaphragm on sonography, but were unable to undergo studies of phrenic nerve function before death from metastatic disease. It is suggested that right phrenic nerve palsy is a late complication of an indwelling central venous catheter.