For nearly three quarters of a century bone islands (enostoses) were considered scintigraphically inactive, hence, easily differentiated radiologically from clinically more significant primary or metastatic intraosseous lesions. However, enostoses' clinical significance has changed considerably since the first report of a case with increased radioactive uptake on bone scan in 1976. Consequently, any radiotracer-positive skeletal lesion, regardless of radiographic appearance and clinical presentation, is now generally viewed with some caution. A 23-year-old woman presented with polyostotic enostoses discovered incidentally during pelvic radiographic examination. Both scintiscan and skeletal survey identified one or three fairly large densely radiopaque lesions in many bones, the largest measuring 7 x 4 cm. Except for a few departures from characteristic radiologic and scintigraphic changes, such as lesional border alterations and considerable increase in size and number of lesions involving many bones (polyostotic), the clinical findings and radiographic appearance of every bone island seem typical. Absent definitive roentgenologic diagnosis, both needle and open biopsies were performed. We found no previous report of a polyostotic enostoses with or without positive radionuclide bone scans reported in the literature. Distinctions from osteopoikilosis and osteopathia striata are briefly discussed.