Cranial computerized tomography was performed in 145 patients with petit mal epilepsies. Tomographic results were compared to clinical data, 59 patients (41%) had normal findings, in 39 children (27%) the authors found slight pathologic changes. In 33 (22%) medium-degree changes, and in 14 children (10%) severe pathologic changes were seen. West syndrome: (N = 19). 18 patients with pathologic findings. The combination of cortical plus subcortical atrophies (N = 11) was observed most frequently. Atrophies were of mostly severe or medium degree. Lennox syndrome: (N = 31). 28 patients (90%) had pathologic results; subcortical atrophies (N = 19) prevailed. Centrencephalic myoclonic-astatic petit mal: (N = 43). 26 normal and 17 (40%) pathologic findings at CTAT. Pathologic findings were mostly grouped as slight (N = 13), with subcortical atrophies again prevailing. However, there was a statistically significant difference from Lennox syndrome as far as frequency and severity of pathologic changes are concerned. Absence epilepsy: (N = 49). There were 29 normal results and 20 (41%) pathologic findings. Slight atrophies were prevailed (N = 14). More favorable findings could be secured statistically in the following subgroups: In primary generalized petit mal epilepsies as compared to secondary generalized types. This applies to frequency as well as severity of pathologic findings. In centrencephalic myoclonic-astatic petit mal during infancy as compared to children with secondary generalized petit mal during this age. In petit mal seizures without concomitant grand mal seizures if compared to the group with concomitant grand mal. In cryptogenetic primary generalized petit mal epilepsies if compared to non-cryptogenetic forms. In patients without microcephalus if compared to those with microcephalus.