We studied the clinicopathologic features of pulmonary hemorrhage in autopsied infants less than 1 year of age for a 12-month period. There were 70 liveborns (LB) and 24 stillborns (SB). The percentage of LB with pulmonary hemorrhage (PH), pulmonary interstitial emphysema (PIE), hyaline membrane disease (HMD), acute bronchopneumonia (ABP), congenital malformations (CM), and surgery (SUR) were analyzed according to weeks of estimated gestational age (EGA) and as an entire group. Overall, 74% of LB and 24% of SB had histologic evidence of PH. A semiquantitative evaluation of the extent of PH among the LB infants disclosed that hemorrhage involved less than one-third of the observed lung tissue in 42%, one-third to two-thirds of the lung was hemorrhagic in 15%, and the remaining 42% had more than two-thirds hemorrhagic lung parenchyma. A total of 31 clinical and pathologic factors were evaluated for their possible association or relationship to PH. Statistical analysis revealed that hyaline membranes and hemorrhage in other extrapulmonary sites were the only significant associations with PH. PH was more frequent in premature infants born between 24 and 39 weeks EGA and was always associated with multiple other conditions. Although the autopsy finding of hemorrhage in the lungs is relatively frequent in the population we studied, it appears that PH as a primary phenomenon in infants is extremely rare, if it occurs at all.