This study investigated whether the moon effect might increase incidence of injuries & patient admissions to emergency rooms on full moon days. During 13 months, 58,000 trauma patients admitted in 3 hospitals in Tehran were studied, with 54,457 cases in the final sample. The number of trauma patients did not increase during the full moon days compared to other days of the lunar month. An association between assault & attempted suicide was not observed around the full moon days either. Further research is called for in order to reach conclusive results. (14 refs.)