Forty four patients suffering from idiopathic inflammatory myopathies (IIM) were included in the present study, fulfilling the diagnostic criteria of IIM according to Bohan and Peter criteria in 1975, in addition to twenty two normal healthy individuals who served as control. They were subjected to full history taking, clinical examination and laboratory investigations. Gray scale sonography (GSS) and power Doppler sonography (PDS) were done to detect and quantify the inflammatory process of muscle and to correlate these findings with the patients' history, clinical and laboratory findings aiming to develop sensitive method for staging of disease activity and severity. Abnormal findings on GSS (higher scores) indicating muscle atrophy were associated with longer disease duration. In contrast, PDS findings of increased vascularity appeared to be detected in shorter disease duration. GSS scores were shown to correlate with muscle biopsy findings of fibrosis. However, this could not be found between PDS (reflecting muscle vascularity) and muscle biopsy findings. There was a significant positive correlation between creatine phosphokinase (CPK) and average PDS scores in the juvenile dermatomyositis group compared to the adult group. Muscle condition was significantly better in patients with juvenile dermatomyositis compared to that of patients with myositis associated with connective tissue diseases and adult polymyositis-dermatomyositis (PM-DM). Muscle condition was significantly better in patients with myositis associated with connective tissue diseases compared to that of patients with adult PM-DM. GSS is a useful approach to the assessment of IIM. PDS, a newer technique, enables detection of muscle vascularity and inflammation.