We conducted a systematic review to determine the safety and efficacy of omega-3 fatty acids for autistic spectrum disorder (ASD). Articles were identified by a search of MEDLINE, EMBASE, and the Cochrane Database using the terms autism or autistic and omega-3 fatty acids. The search identified 143 potential articles and six satisfied all inclusion criteria. One small randomized controlled trial (n = 13) noted non-significant improvements in hyperactivity and stereotypy. The remaining five studies were small (n = 30, 22, 19, 9, and 1) with four reporting improvements in a wide range of outcomes including language and learning skills, parental observations of general health and behavior, a clinician-administered symptom scale, and clinical observations of anxiety. Due to the limitations of evidence from uncontrolled studies and the presence of only one small randomized controlled trial, there is currently insufficient scientific evidence to determine if omega-3 fatty acids are safe or effective for ASD.