Retrospective evaluation of bone scintigrams over the last 10 years was performed to determine the incidence of a solitary hot spot in the skull, examine its significance in patients with and without extra-skeletal malignancy, and determine if location along the suture lines is clinically significant or not. Review of the reports of bone scintigrams in 9968 patients yielded 37 (0.37%) patients with a solitary hot spot in the skull. In the group of 27 patients with extra-skeletal malignancy, the hot spot was secondary to metastasis in four patients and of a non-metastatic origin in 15. In the remaining eight patients, the cause was indeterminate. Two of the four metastatic foci were located along the suture lines. In another group of 10 patients without extra-skeletal malignancy, the cause was non-metastatic in eight patients and indeterminate in two. No significant differences between the scintigraphic features (intensity of uptake, location and relationship with sutures) of metastatic and non-metastatic foci were noted. We conclude that a solitary hot spot in the skull is rare and is predominantly benign in nature. However, in patients with known extra-skeletal malignancy, approximately 21% are secondary to a solitary bone metastasis of the skull. Location of a hot spot along the suture lines may not always be a normal variation and can represent a solitary bone metastasis.