Many patients with epilepsy receive treatment in polytherapy. Selection of antiepileptic drugs (AEDs) for the combination should be carried out in accordance with the principles of rational polytherapy, taking into account the mechanism of action, pharmacokinetic (PK) and pharmacodynamic (PD) properties of drugs. Along with levetiracetam, gabapentin, vigabatrin and pregabalin, lacosamide (LCM) shows superior PK profile in rating of all AED and can be combined with any of them. The goal of this study was to evaluate efficacy and tolerability of LCM in patients with uncontrolled partial onset seizures (POS) in routine clinical practice. Methods. 181 patient’s charts from 14 sites in Russia have been analyzed in retrospective manner. Patients 16 years old and older with POS with or without secondary generalization were included. Documented observation period of up to 12 months after initiation or until discontinuation of LCM therapy. Primary effectiveness variables was retention at Observational Point 3 (approximately 12 months). Other variables were: percentage change from historical baseline in seizure frequency, 50% and 75% treatment response and seizure-free status at the Observational Points 1, 2 and 3 (approximately 3, 6 and 12 months) and incidence and reason of treatment discontinuation. Results. retention rate was high with 89.5% after 12-month observation. The development of seizure frequency showed a continuous decrease in terms of 50%, 75% treatment respond rates and seizure free status. A total of 5 adverse drug reactions leading to discontinuation of LCM therapy were recorded in 5 of 181 patients (2.8%) during the observation period. The high retention rate observed in this retrospective chart review is assumed to indicate a good tolerability and effectiveness of an adjunctive LCM treatment in patients with uncontrolled partial epilepsy in Russia.