The authors describe two cases of parosteal lipoma, an infrequent benign tumour, associated with hyperostosis. The first patient presented with a mass in the posterior neck, the other with one in the proximal forearm. Radiologic diagnosis was facilitated by magnetic resonance imaging (MRI). The MRI images showed the characteristic features of a parosteal lipoma, as well as hyperostotic areas that remained of low signal intensity in both T1-weighted and T2-weighted sequences. MRI is both sensitive and specific for diagnosing these lesions and provides excellent depiction of the anatomic features before surgery.