A hospital emergency department (ED) studied factors that it thought had an effect on the number of patients who left without being seen (LWBS). It analyzed n = 164 24-hour observation periods using six binary predictors representing days of the week, daily occupancy rate, and number of patients presenting to the ED. The fitted regression equation was LWBS = 1.87 + 1.19Mon 0.187Tue 0.785Wed 0.580Thu 0.451Fri 0.267Sat + 0.078Occ + 0.025#PatPres (SE = 6.18, R² = .294, R²_adj = .292).