In the light of alternative conceptions of "two-system" and "single-system" models of language processing the efforts have been undertaken to study brain mechanisnis for generation of regular and irregular forms of Russian verbs. The 19 EEG channels of evoked activity were registered along with casual alternations of speech morphology operations to be compared. Verbs of imperfective aspect in the form of an infinitive, belonging either to a group of productive verbs (default, conventionally regular class), or toan unproductive group of verbs (conventionally irregular class) were presented to healthy subjects. The subjects were requested to produce first person present time forms of these verbs. Results of analysis of event related potentials (ERP) for a group of 22 persons are presented. Statistically reliable ERP amplitude distinctions between the verb groups are found onlyin the latencies 600-850 ms in central and parietal zones of the cortex. In these latencies ERP values associated with a presentation of irregular verbs are negative in relation to ERP values associated with the presentation of regular verbs. The received results are interpreted as a consequence of various complexity of mental work with verbs of these different groups and presumably don't support a hypothesis of universality of the "two-system" brain mechanism for processing of the regular and irregular language forms.