The aim was to determine the direct medical costs in patients with partial refractory epilepsy at the Mexican Institute of Social Security (IMSS) in Mexico. We carried out a multicenter, retrospective-cohort partial-economic evaluation study of partial refractory epilepsy (PRE) diagnosed patients and analyzed patient files from four secondary- and tertiary-level hospitals. PRE patients >12 years of age with two or more antiepileptic drugs and follow-up for at least 1 year were included. The perspective was institutional (IMSS). Only direct healthcare costs were considered, and the timeline was 1 year. Cost techniques were microcosting, average per-service cost, and per-day cost, all costs expressed in U.S. dollars (USD, 2004). We reviewed 813 files of PRE patients: 133 had a correct diagnosis, and only 72 met study inclusion criteria. Fifty eight percent were females, 64% were