Functional MRI was used to evaluate factors influencing hemispheric dominance for language in 34 children suffering from intractable focal epilepsy due to left hemispheric lesion of pre- (n = 19) or postnatal (n = 15) origin. Nineteen children (56%) exhibited pronounced left-hemispheric language dominance. Significant co-activation of the right hemisphere or a complete language shift to this hemisphere was present in 15 children (44%). Atypical language representation was detected in 6 children (31,6%) with developmental pathology and in 9 patients (60%) with acquired epileptogenic lesion. Younger age at epilepsy onset and longer duration of epilepsy correlated significantly with atypical language presentation (p < 0,017 and p < 0,025). Whereas lesser tendency of prenatal lesions to displace cortical language centers did not reach statistical significance in simple paired tests, multiple logistic regression analysis viewed positive interaction between language shift, etiology and age at epilepsy onset. In conclusion, the language network reorganization was strongly influenced by both, the age at epilepsy onset and duration of epilepsy, and to a lesser degree by the character of the epileptogenic lesion, either developmental or acquired postnatally.