The size of segmental liver grafts assessed by preoperative computed tomography (CT) volumetry was evaluated in relation to surgical outcome in 14 living related partial liver transplantations (LRLTs). The aim was to show that graft size can be accurately assessed before operation and to estimate the lower safety limit of graft size in assessing subsequent graft function and survival. The relationship between calculated CT volume and weight of the liver was linear in the recipient (r = 0.97) and donor (r = 0.98). The mean (s.e.m.) modified liver weight ratio (MLWR; ratio of graft weight to recipient's expected liver weight based on body-weight) was 0.59(0.07) (range 0.27–1.09). Surgical complications related to an oversized graft and primary graft failure caused by a small-for-size graft were not observed. The lowest MLWR of any survivor was 0.27. These results suggest that a partial liver graft reduced to about 30 per cent of the recipient's expected liver weight can tolerate LRLT well.