The amount of traumatic hematuria induced by urethral catheterization was studied by comparing the pre- and post-catheterization urinalyses of 93 patients presenting to the emergency department with abdominal complaints of an acute nature. Thirty-nine male patients ranging in age from 4 to 91 years and 51 female patients ranging in age from 1 to 70 years were studied. Catheterizations were performed by nurses (54%), resident house-staff (38%), and nurse practitioners (8%). Overall, hematuria was induced in 16 of 93 patients (17.2%) and, when present, never exceeded 3 RBC/hpf.