Purpose: We evaluated the frequency, distribution and appearance of skeletal metastases with ¹⁸F-sodium fluoride PET (¹⁸F-PET). Between 3/96 and 5/97, ¹⁸F-PET was performed in 58 patients with solid carcinomas in addition to conventional planar bone scintigraphy. Results: The distribution and appearance of 130 bone metastases could be evaluated. Of these, 62% were located in the spine. Osteolytic metastases were characterized as photopenic lesions surrounded by a rim of increased activity. Osteoblastic metastases present as areas of locally increased tracer accumulation, which could be differentiated from degenerative lesions only by means of EXACT anatomic localization. Conclusion: Bone imaging with ¹⁸F-PET allows detection and differentiation of benign from malignant bone lesions with high specificity. Osteolytic metastases show a very characteristic pattern of tracer accumulation and could be easily differentiated from benign lesions. In osteoblastic metastases, the superior spatial resolution of the PET technique allows the exact anatomic localization and reliable differentiating between degenerative lesion sand metastases in most cases.