: Autism is associated with a high frequency of epileptiform EEG abnormalities (prevalence range 10.3-72.4%) and epilepsy (prevalence range 0-44.5%). A significant subgroup of autistic children (20-49%) experience autistic regression. The relationship among EEG abnormalities, epilepsy, and regression in autistic patients is not yet well understood. In this review, the current knowledge of the relationship is summarized. The evidence from clinical studies does not support the view that EEG abnormalities play a role in autistic regression. The majority of studies also failed to find any significant relationship between epilepsy and autistic regression. However, some results indicated that the higher the prevalence of epilepsy in the sample, the greater the probability of there being a significant association between epilepsy and autistic regression. Further research on the topic is needed.