One hundred fifty-six children younger than 13 years of age with blunt abdominal injuries were reviewed, and those injured in accidents (89%) were compared with those injured by child abuse (11%). Abused children were younger (mean age, 2 1/2 years) and all presented late to medical attention with a history that was inconsistent with their physical findings. Only 65% of abused children had physical or roentgenographic signs of prior abuse, while 35% had no signs of prior abuse. The abdominal organs injured were different; 61% of accidentally injured children suffered injuries to a single, solid organ, and only 8% had hollow viscus injuries, while 65% of abused children had hollow viscus injuries. Physicians should suspect child abuse when children have unexplained injuries (especially young children with hollow viscus injuries) even when other signs of child abuse are absent, and they should suspect hollow viscus injury in abused children.