We tried to measure anxiety levels in emergency medical service (EMS) providers to determine the effects of (1) having had a violent encounter during a shift and (2) different shift schedules, conducting a prospective observational study over 3 months in an urban EMS system setting. A convenience sample of 23 EMTs and 40 EMT-Ps was observed. Anxiety levels were measured using the Spielberger State-Trait Anxiety Inventory. A total of 99 inventories were completed by 63 EMS providers. The mean state (32.6+/-8) and trait (31.7+/-7.1) scores were less than normative scores (35.7+/-10.4 and 34.9+/-9.2 respectively) for working adult males (P = .004 and .007, respectively). Paramedics had lower anxiety scores than basic EMTs (P = .015 and .039) and years of experience also decreased anxiety scores (P < .0001). There was no significant difference in state scores between those EMS providers who had encountered violence during the preceding 12 hours and those providers who had not. Comparisons of state scores of providers assessed at hour 12 of a 12 hour shift, hour 12 of a 24 hour shift, and hour 24 of a 24 hour shift failed to show any significant differences. Although the working environment of the EMS provider contains numerous stressors and uncertainties, this population of providers were no more anxious than the general working public. Advanced training and years of experience decreased anxiety. Violent encounters during a shift did not appear to affect anxiety levels. There was no difference in anxiety levels in providers who worked 12 and 24 hour shifts.