Pulmonary disease is a complication of Gaucher disease (GD), a lysosomal disorder due to the deficiency of glucocerebrosidase. Lung involvement was investigated through chest radiography, high-resolution computed tomography of the chest, pulmonary function tests (PFT), and oxygen saturation (SaO2) at 21% FI(O2) in 13 Italian GD patients, six homoallelic for the L444P mutation (Group A), seven with various genotypes (Group B). Echocardiography and transcutaneous oxygen tension measurement at room air and after breathing 100% oxygen were performed to exclude pulmonary hypertension and/or intrapulmonary shunts. A score index (SI) including lung involvement evaluated the severity of GD. In three Group A patients with respiratory symptoms and in an asymptomatic male interstitial involvement was demonstrated; one child died of aspiration pneumonia. Group B patients had no signs of lung damage; PFT were normal in all cases but one. SaO2 was normal in both groups. Pulmonary vascular disease was ruled out in three cases with respiratory symptoms. In Groups A and B the median SI were 22 and 13, respectively (p < 0.01). L444P homozygotes appear at major risk for developing pulmonary disease, even at earlier ages. A comprehensive evaluation of lung involvement is recommended primarily in these subjects.