Homocysteine (Hcy) is an important product of the intermediary metabolism. Even a mild increase is a risk factor of vascular damage, in particular of peripheral, cerebral and coronary arteries. Its marked neurogenic excitatory effect is also known and it is used as an epileptogenic agent in experimental models of epilepsy. Metabolic disorders leading to a general rise of total plasma homocysteine (tHcy) are closely associated with deficiency of B vitamins - folate, vitamin B 12, pyridoxine. The authors submit results of assessment of plasma tHcy and vitamins in a group of 82 patients treated by classical antiepileptics (AE). In a group of 35 patients with elevated values of tHcy - above 10.3 in women and 12.5 m mol/l in men, statistically significantly lower folate values were found (on account of the group of men), of vitamin B12 (equally in men and women) and of pyridoxine (in women) as compared with a group of 47 with lower values of tHcy. In the mentioned group of 35 patients only slightly elevated values of tHcy predominated. In those instances it may be assumed that there is an association with vitamin deficiency due to AE therapy. The finding of medium elevated tHcy was recorded in three men, suspected deficiency of the MTHFR enzyme (methylenetetrahydrofolate reductase) within the frame- work of the metabolic deviation with autosomal recessive heredity was confirmed so far in one patient. The EEG and clinical follow up of the influence of medium grade hyperhomocysteinaemia (HHcy) in patients after an acute methionine loading test did not provide evidence of a direct e pileptogenic effect (in 7 patients). Despite this it may be assumed that a metabotropic effect on neurogenic mechanisms cannot be ruled out during long-term latent action in particular in non-treated patients. The findings of interrelated HHcy and deficiency of the vitamin B group in epileptology may be important from theaspect of the course, etiology and coincidence with vascular damage. As substitution of deficient vitamins led to normalization of tHcy levels, their aimed administration may be recommended.

        Key words: homocysteine, hyperhomocysteinaemia, folate, vitamins of the B group, epilepsy