Autism is a complex neurological disorder that severely impacts a child's ability to communicate and interact socially. Many treatments have attempted to alleviate the symptoms of autism, but with limited success. After reports of improvements in autistic children who received secretin, this hormone became popular as a possible treatment for autism. Since then, the interest in secretin has greatly increased, as well as the demand for secretin by parents of autistic children. However, there is still limited experimental evidence that supports its effectiveness. Many biological studies and clinical trials were conducted to test the effectiveness of secretin in treating autism. This review discusses the autistic disorder, instruments used in the trials, and reports the findings of some of these studies.