Nonoperative management (NOM) of blunt liver or spleen injuries (LSI) is widely accepted, but diaphragmatic injuries (DI) can be elusive. We hypothesize that rib fractures and minor LSI (RF+ minor LSI) are associated with DI. Patients with blunt injury undergoing exploratory laparotomy between January 1, 2000, and December 31, 2007, were identified from our registry. The association between injury variables and DI was examined with logistic regression. Organ Injury Scores of the liver and spleen of Grade I/II were defined as "minor." A potentially nonoperative (PNO) patient had a rib fracture and minor LSI but no bowel injury or hypotension (systolic blood pressure less than 90 mmHg). The incidence of DI was 7.5 per cent (53 of 705) overall but 20 per cent (seven of 35) in patients with RF + minor LSI. Nineteen PNO patients had four (21.1%) DIs. RF + LSI (3.26 [1.74-6.12], P < 0.001) and motor vehicle collisions (4.93 [2.36-10.32], P < 0.001) were independently associated with DI. The incidence of laparotomy in all critically ill blunt injury patients (n = 2177) decreased significantly (P = 0.003). RF + minor LSI are associated with DI even when there are no other operative injuries. Because NOM is increasingly accepted, the potential for missed DI exists. When high-quality imaging is not available or is equivocal, further studies should be considered.