This investigation studied the neuropsychological differences in nonsurgical cryptogenic epileptic patients with seizures of frontal and temporal lobe origin, which were classified according to clinical criteria. Fifty-one patients with partial seizures of frontal (n = 15) or temporal (n = 36) lobe origin and 2 matched control groups were administered a battery of neuropsychological tests assessing intelligence, memory, perceptual, and frontal functions. Patients with seizures of temporal lobe onset performed worse than patients with seizures of frontal lobe origin, even in frontal functions. The findings of this study corroborate the low specificity of tasks regarded as frontal lobe tests and the difficulty in detecting frontal lobe neuropsychological focalities.