Introduction: idiopathic inflammatory myopathies are systemic autoimmune disorders of unknown origin. Therefore other organs such as the lungs may be affected. The association of interstitial lung disease with dermatomyositis and polymyositis has been well established. Purpose: To assess frequency of pulmonary involvement in dermatomyositis and polymyositis in investigated Egyptian patients.Subjects and methods: twenty patients with dermatomyositis and polymyositis were investigated. No patient had any signs or symptoms of pulmonary infection at the time of the study. All patients (20 patients) and controls (7 controls) were subjected to bronchoscopy with bronchoalveolar lavage sampling to detect alveolitis. Results: All of the twenty patients showed elevated neutrophilic and lymphocytic counts in the results obtained from the analysis of the samples. Five patients showed signs of lung affection by noninvasive methods (X-ray and HRCT). Conclusion: We demonstrated that patients with polymyositis and dermatomyositis often suffer from clinical and sub-clinical lung disease in the form of alveolitis with or without interstitial lung fibrosis even though the myositis was adequately controlled by corticosteroid and immunosuppressive therapy. BAL provides an excellent demonstration of the lung involvement in patients with polymyositis and dermatomyositis and associated interstitial lung disease. The need for further follow-up studies to determine the effectiveness of intensified treatment in these patients is emphasized.