The value of CT, conventional radiography and ultrasound was compared in 40 patients with 52 skeletal metastases. For superficial lesions, the combination of sonography and conventional radiography was equivalent to CT in showing the extent of bone destruction and soft tissue involvement. As expected sonography was unsatisfactory for deeper lesions. Sonography can provide useful information for planning radiation therapy for superficial lesions, but it does not replace conventional radiography.