Bone single photon emission tomography (SPET) of the knees has been shown to be of diagnostic value for the investigation of knee pain. This study compared bone SPET with magnetic resonance imaging (MRI) for the diagnosis of knee disorders. Thirty-six patients were studied with both modalities, performed an average of 4 months apart (range 0–10 months). There was agreement on the presence or absence and nature of pathology in 24 (67%) patients. In a further three patients, there was an abnormal SPET with equivocal change for the same pathology on MRI. Equivocal changes on both modalities for the same pathology were found in one patient. Three patients had abnormalities on MRI with normal SPET, with the remaining patients having equivocal or non-specific changes on one modality only. In the majority of patients, there was agreement on the presence or absence of pathology and the nature of pathology with both modalities. Significant pathology detected on MRI was also identified by bone SPET. This initial study suggests that further work should be undertaken to evaluate the role of bone SPET as a screening test for the evaluation of knee disorders and its role in relation to MRI is justified.