Bone single-photon emission tomography (SPET) was performed in 40 patients within 6 months of acute knee injury where internal derangement of the knee was suspected, and the results related to the arthroscopy findings. Scan features with high sensitivity, specificity, and predictive accuracy for a meniscal tear could not be obtained on planar imaging. However, a half-crescent or more of increased tibial plateau activity on transaxial SPET gave a sensitivity of 89%, a specificity of 76%, a positive predictive accuracy of 77% and a negative predictive value of 89%. For longitudinal (bucket handle) tears alone the optimum scan pattern was a full crescent of increased tibial plateau activity with adjacent femoral activity and increased blood pool activity which gave corresponding values of 78%, 94%, 78% and 93%. It is concluded that the inclusion of tibial plateau activity of less than a full crescent and the presence of femoral condyle and blood pool activity in the diagnostic criteria improves the ability of bone SPET to detect meniscal tears. The value of bone SPET in the diagnosis of meniscal tears suggests that it could have a significant role to play in the management of knee injuries.