The objective of this study was to compare Tc-99m MDP bone and Ga-67 scans for the therapeutic response to bone lymphoma in 40 patients. The authors retrospectively compared 40 Tc-99m MDP bone scans and 20 Ga-67 scans before therapy, 29 bone scans and 13 Ga-67 scans during the therapy, and 33 bone scans and 15 Ga-67 scans after therapy. Tc-99m MDP and Ga-67 whole body scans were obtained within 2 weeks of each study and were graded visually (grades 1-4) in which grade 3 means similar count density to that of normal iliac alar activity on bone scans and normal liver activity on Ga-67 scans, respectively. The findings of lesion improvement during and after therapy were found in 66.0% (19 of 29) and 72.7% (24 of 33) with Tc-99m MDP bone scans, 84.6% (11 of 13) and 86.7% (13 of 15) with Ga-67 scans, respectively. The mean grades of Tc-99m MDP uptake were 3.06 before, 2.34 during, and 1.75 after therapy. The mean grades of Ga-67 uptake were 3.22 before, 1.42 during, and 1.30 after therapy. Ga-67 scans appear to be more reliable than Tc-99m MDP bone scans in evaluating the therapeutic response of bone lymphoma.