The function of the shoulder after removal of the vascularized latissimus dorsi muscle in seventeen patients was compared with the function of the shoulder in seventeen control subjects. Physical examination of the extremity and instrumented muscle-testing were used to evaluate both the patients and the control subjects, and the patients also completed a questionnaire. Thirteen patients rated the appearance of the donor extremity as good, and sixteen patients perceived no functional impairment of the donor extremity. The range of motion of both shoulders was symmetrical in eleven patients and fourteen control subjects. Manual muscle-testing showed normal strength of the latissimus dorsi bilaterally in seven patients and in thirteen control subjects. Nineteen instrumented isometric, isotonic, and isokinetic tests were performed to assess the strength of each shoulder of all of the patients and control subjects, and the results in these two groups were then compared. there was no statistically significant difference in the strength of the two shoulders between the patients and the control subjects, with the exception that the patients exhibited weakness in the amount of isokinetic torque during extension of the shoulder with the limb in a position of 60 degrees of flexion and at a speed of 60 degrees per second. On the basis of these findings, and because of the inherent inaccuracy of manual muscle-testing, we concluded that transfer of the vascularized latissimus dorsi muscle had little effect on the range of motion, muscular strength, and function of the donor shoulder in our patients.