Inclusion Criteria:
* Meets DSM-IV, ADI, and ADOS criteria for autistic disorder
* Age 5-17.
* Outpatients
* Parent or legal guardian signing informed consent, and assent documented for patient with demonstrated capacity to provide it.
* Sexually active females of childbearing potential must use an acceptable method of birth control (oral contraceptive medications \[the administration of which must be supervised by a parent or guardian\], IUD, depot medication, double barrier or tubal ligation) and have a negative serum pregnancy test prior to entry into the study.
* Subjects with history of seizures, who have been seizure-free for more than or equal to 6 months on a stable dose of anticonvulsant medication.Non-medicated subjects with a history of seizures who have been seizure-free for more than or equal to 6 months.Subjects with abnormal EEG but no clinical seizures.
Exclusion Criteria:
* Subjects who are pregnant or nursing mothers.
* Sexually active females of childbearing potential who are not using adequate birth control measures (detailed above in inclusion criteria).
* Subjects with overall adaptive behavior scores below the age of two years on the Vineland Adaptive Behavior Rating Scale.
* Subjects with active or unstable epilepsy.
* Subjects with any of the following past or present mental disorders: schizophrenia, schizoaffective disorder, major depressive disorder, bipolar I or II disorders or substance abuse disorders.
* Subjects who are a serious suicidal risk.
* Subjects with clinically significant or unstable medical illness that would contraindicate participation in the study, including hematopoietic or cardiovascular disease, pancreatitis, liver toxicity, and polycystic ovary syndrome
* Subjects reporting history of encephalitis, phenylketonuria, tuberous sclerosis, fragile X syndrome, anoxia during birth, pica, neurofibromatosis, hypomelanosis of Ito, hypothyroidism, Duchenne muscular dystrophy, and maternal rubella.
* Patients with history of the following:gastrointestinal, liver, or kidney, or other known conditions which will presently interfere presently with the absorption, distribution, metabolism, or excretion of drugs, cerebrovascular disease or brain trauma, clinically significant unstable endocrine disorder, such as hypo- or hyperthyroidism, recent history or presence of any form of malignancy
* Treatment within the previous 30 days with any drug known to a well-defined potential for toxicity to a major organ
* Subjects with clinically significant abnormalities in laboratory tests or physical exam
* Subjects likely to require ECT.
* Subjects unable to tolerate taper from psychoactive medication if necessary.
* Subjects with a history of hypersensitivity or severe side effects associated with the use of divalproex sodium, or other an ineffective prior therapeutic trial of omega three fatty acids.
* Subjects who have received any of the following interventions within the prescribed period before starting treatment-investigational drugs within the previous 30 days.
* Subjects who have begun any new alternative non-medication treatments, such as diet, vitamins, and psychosocial therapy, within the previous three months.
* Subjects with any organic or systemic disease or patients who require a therapeutic intervention, not otherwise specified, which would confound the evaluation of the safety of the study medication.
* Subjects who reside in a remote geographical area who do not have regular access to transportation to the clinical facility.
* If a patient is not doing well enough (defined by CGI-AD Severity score of 3-"mildly ill" or better)
