['Video-EEG monitoring in the epilepsy monitoring unit (EMU) is a limited clinical resource. Knowledge of the predicting factors for length of stay (LOS) in the EMU may allow providers to more efficiently utilize EMU bed space.', 'The records for all consecutive admissions to the EMU at the University of Colorado Hospital between December 1, 2010 and May 31, 2011 (n = 142) were retrospectively reviewed.', 'Univariate analyses focusing on variables known prior to admission showed that EMU LOS (in hours) was not significantly correlated with patient age, number of event types, or number of antiepileptic drugs at admission. Patients who were admitted to the EMU for event characterization had statistically significantly shorter average LOS than patients who had been admitted as a part of a presurgical evaluation. Patients who reported < = 1 seizure per week had a statistically significantly higher average LOS than patients who reported >= 1 seizure per day. These variables were also significantly predictive of total LOS (p < 0.0001 and p = 0.03, respectively) in multivariate analysis.'] Do pre-admission clinical factors affect length of stay in the epilepsy monitoring unit?