The T1 and T2 relaxation times of primary tumors of the musculoskeletal system were calculated in 54 patients. No correlation was found between the relaxation values and the histopathologic type of the tumors. Lipoma had the same relaxation characteristics as normal fat. Otherwise tumors could be differentiated from normal tissue, but there was no significant difference between malignant and benign tumors, and the mean values for the different histopathologic types differed significantly only in a few instances. Hence T1 and T2 measurements are of limited value for histologic characterization of musculoskeletal tumors.