Dendriform pulmonary ossification is an extremely rare disease, which is usually found and analysed postmortem. Pathogenesis of pulmonary ossification is therefore still unknown. We describe two males in the same family (a 29 year-old patients and his 58 year-old father) with pulmonary ossification. The young male was symptomatic pneumothorax but his father had been asymptomatic since youth. Familial clustering of pulmonary ossifications strongly suggests a genetic predisposition for the pathogenesis. This is the first report of two cases of dendriform pulmonary ossification in the same family.