In 1998, Horvath et al. [Horvath, K., Stefanatos, G., Sokolski, K. N., Wachtel, R., Nabors, L., & Tildon, J. T. (1998). Improved social and language skills after secretin administration in patients with autism spectrum disorders. "Journal of the Association of the Academy of Minority Physicians," 9, 9-15] reported an uncontrolled trial of secretin with three participants with autism, which apparently resulted in significant behavioral improvement. Subsequently, secretin was widely used. Sandler et al. [Sandler, A. D., Sutton, K. A., SeWeese, J., Girardi, M. A., Sheppard, V., & Bodfish, J. W. (1999). Lack of benefit of a single dose of synthetic human secretin in the treatment of autism and pervasive and developmental disorder. "The New England Journal of Medicine," 341, 1801-1806] reported the first double-blind trial of secretin with negative results. This article is a review of 15 double-blind trials of secretin. Almost none of the studies reported any significant effects and none concluded that secretin was effective. Transient effects of secretin, including both minor benefits and behavioral deterioration were reported, probably due to multiple statistical tests. Four papers reported data on differential responding in sub-groups of participants, including those with gastrointestinal symptoms. These effects were not replicable. At this time there is no robust evidence that secretin is an effective treatment for pervasive developmental disorders.