Abstract Mutation in the protocadherin 19 (PCDH19) gene is an increasingly recognized cause of epilepsy in females. This disorder is frequently associated with mental retardation and psychiatric features. We describe two unrelated females with novel PCDH19 missense mutations. One was de novo , and the other was inherited from her unaffected father. Both had mild mental impairment but had remarkable behavioral problems. We reviewed the cognitive and behavioral profiles of previously reported PCDH19-positive cases. Intellectual disability appeared in 75% of patients, ranging from borderline to severe. More than half of the individuals presented behavioral disturbances, which could be divided into two different groups: autistic and non-autistic. The majority of patients with autism already had some degree of cognitive impairment. It appears that seizures tend to diminish or even stop in adolescence, so non-epileptic problems can become the most important and disabling issue in adult patients with PCDH19 mutation.