This study was undertaken to assess the effects of certain common modes of load carrying by hand in the BK amputee-PTB prosthesis system. The energy costs of a test group consisting of BK amputees using PTB prostheses were compared to those of a control group made up of normal able-bodied individuals and the difference between the two groups was observed to be more marked when walking was performed on the level with load in one hand only in comparison with the both-hand carrying conditions. Single handed load carrying by either hand did not seem to make any observable difference. Stair ascending with equal load in both hands did not produce any appreciable difference between the two groups. Indications were obtained that the BK amputee with a PTB prosthesis system is capable of performing industrial tasks of "moderate" grade.