Radioisotopic bone scans and radiography were used to detect bone neoplasms in 144 dogs that inhaled alpha-particle-emitting 238PuO2 particles. Radiography was used routinely to survey the skeleton of the dogs. Nineteen dogs developed bone neoplasms; 17 of these were studied with bone scans and radiography; both methods showed a high degree of success in detecting bone neoplasms. Predominant regions of occurrence have been the lumbar region of the spine and the humerus. The bone scanning method used gamma-camera detection of IV injected 99mTc-labeled methylene diphosphonate. All neoplasms detected radiographically also were identified by bone scans. In addition, 3 lesions confirmed histologically as osteosarcomas were detected by bone scanning, but were missed by radiography. Bone scanning was a more sensitive means for the detection of bone neoplasms than were routine radiographic procedures.