Episodic ataxia type 2 (EA-2) is a rare neurological disorder of the autosomal dominant inheritance classified to the channelopathies (mutation in the calcium channel gene CACNA1A located on chromosome 19p13). EA-2 is characterized by episodes of the ataxia commonly triggered by physical and emotional stress, exercises, fatigue, alcohol. Between episodes of the ataxia the most common neurologic finding is isolated nystagmus. The authors report 22-year-old women hospitalized because of vertigo and gait imbalance. Exercise-induced attacks of incoordination recurred at least once a half-year, since age 18 years. On examination during an acute episode patient exhibited ataxia and horizontal nystagmus. During hospitalization we ruled out the diseases, which may cause episodic ataxia. The ataxia withdraw after treatment of acetazolamide, gait imbalance abated. Between attacks the horizontal nystagmus were found on neurological examination. The history of the patient family was uncompleted because she was adopted. The follow-up is continued and the patient hasn’t new attacks of ataxia. This EA-2 is the first case reported in Poland.