This study is an 8-week open-label trial testing oxytocin nasal spray (Syntocinon) as a treatment for social impairment in adolescents with autism spectrum disorders (ASD). We hypothesize that oxytocin nasal spray will be safe, tolerable, and effective in improving the core symptoms of autism spectrum disorders in adolescents ages 11-17.

Inclusion Criteria

1. Male and female outpatients ages 11-17 years
2. DSM-IV-TR PDD diagnosis of autistic disorder, Asperger's disorder, or PDD-NOS as established by clinical diagnostic interview and with the aid of the MGH ASD Symptom Checklist (MGH-ASD-SCL).
3. At least moderate severity of ASD impairment as measured by a raw score of ≥80 on the SRS and a severity score of ≥4 on CGI-PDD.
4. Participants and their parent/guardian must be able to speak and understand English sufficiently to comprehend the nature of the study and to allow for the completion of all study procedures required per protocol.
5. Subjects and their parent/guardian must be considered reliable reporters.
6. Each subject and their parent/guardian must understand the nature of the study and provide written informed assent/consent.
7. Subjects must be able to participate in mandatory blood draws.
8. Subjects with mood, anxiety, or disruptive behavior disorders will be allowed to participate in the study provided they do not meet any exclusionary criteria.

Exclusion Criteria

1. IQ <85
2. Total lack of spoken language
3. DSM-IV-TR PDD diagnosis of Rett's disorder or childhood disintegrative disorder.
4. Clinically unstable psychiatric conditions or judged to be at serious suicidal risk as determined by evaluating investigator.
5. History of substance use (except nicotine or caffeine) within past 3 months
6. Serious, stable or unstable systemic illness including hepatic, renal, gastroenterological, respiratory, cardiovascular (including ischemic heart disease), endocrinologic, neurologic, immunologic, or hematologic disease.
7. Subjects with severe hepatic impairment (LFTs > 3 times ULN) and those with severely impaired renal function (eGFR < 30).
8. Pregnant or nursing females.
9. Known hypersensitivity to oxytocin.
10. Severe allergies or multiple adverse drug reactions.
11. A non-responder or history of intolerance to oxytocin, after treatment at adequate doses as determined by the clinician.
12. Subjects with significant nasal pathology (including atrophic rhinitis, recurrent nose bleeds, and history of hypophysectomy).
13. Investigator and his/her immediate family defined as the investigator's spouse, parent, child, grandparent, or grandchild.
14. Currently enrolled or recently participated (within the past 6 months) in a clinical trial of intranasal oxytocin.

8 weeks (from baseline to end of study)