A postmortem study investigated 80 infant deaths from head trauma to identify the roles of shaking and direct impacts. Evidence of shaking was defined as two or more of the following: finger marks or rib fractures; subdural or subarachnoid hemorrhage; or a history of vigorous shaking. Shaking to the exclusion of other head trauma was defined as the presence of two or more of the above together with the complete absence of scalp or skull injuries. Nine of the study deaths qualified as exclusively shaking injuries by this definition. Thirty of the deaths had direct injuries as well as two of the criteria of shaking; these deaths were classified as combined shaking and blunt trauma. Forty-one of the deaths had impact injuries without having two of the criteria of shaking. The extent of ocular injuries was reviewed in all cases. Ocular hemorrhages were found with increased frequency in cases with two or more of the criteria of shaking compared to cases with only impact mechanism of injury. Retinal hemorrhages continue to be a good marker of infants injured by vigorous, intentional shaking. Most, but not all, shaken babies have impact injuries as well. Tables, references