We describe the clinical presentation, pulmonary function tests, chest radiograph, and computed tomography findings, response to hormonal treatment, and duration of survival of nine patients with pulmonary involvement in tuberous sclerosis complex with follow-up over an average of 17 years (range, 1 to 35 years) since diagnosis. All patients were female, and the average age at onset of symptoms was 16 years (range, 3 months to 39 years); pulmonary symptoms did not develop until an average age of 33 years (range, 22 to 46 years). There was an average delay of 8 years before the correct diagnosis was made. The most common presenting clinical features were seizures, pneumothorax, bleeding into a renal angiomyolipoma, dyspnea, and typical skin changes. Pulmonary function tests commonly demonstrated obstruction to airflow and reduced single-breath diffusing capacity. Chest radiograph and computed tomography characteristically demonstrated diffuse interstitial infiltrates with cystic changes. Two asymptomatic patients with mild pulmonary involvement have remained in stable condition without hormonal therapy. The remaining seven patients had moderate to severe airflow obstruction; of these, five underwent hormonal therapy. Three patients had a clinical response to treatment. Two patients who did not receive hormonal treatment died of progressive respiratory failure. Most patients with pulmonary involvement in tuberous sclerosis have a slowly declining clinical course. Although the available data are limited, they suggest that a trial of hormonal therapy is recommended both for symptomatic patients and for those with declining pulmonary function. Tuberous sclerosis complex should be suspected in all patients with the diagnosis of lymphangioleiomyomatosis.