Autism is a seriously disabling, distressing and costly life-long disability. A diagnostic hallmark of autism is a qualitative impairment in reciprocal social interaction, including failure to adequately use eye-to-eye gaze, recognize emotion, and regulate social interactions. Research shows the neuropeptide oxytocin (OT) modulates social behavior. In mice, rats, monkeys, and sheep, for instance, central administration of OT administation enhances social recognition, memory for peers, development of partner preference and bonding, while reducing predatory aggression. In humans, OT nasal spray can impressively impact on social cognition, including eye gaze, emotion recognition, and social interaction behavior. These effects have also been shown in patients with autism. The therapeutic effectiveness of OT nasal spray may, however, be limited, partly because it does not readily pass the blood-brain barrier. An alternative approach is to stimulate OT release through alternate and peripheral mechanisms. Melanocortin 4 receptor (MC4-R) stimulation, in particular, has been shown to induce central but not peripheral release of OT. In humans, PT-141 is a noted safe and effective synthetic peptide that acts on melanocortin receptors. We conduct the first study of PT-141 nasal spray to determine its effects on social cognition in humans. A total of 60 neurotypical participants and 60 participants diagnosed with autism receive PT-141 nasal spray (7mg, N = 30) or placebo at the first assessment session, and then the alternate spray at the second assessment session. Following drug administration, participants complete experimental tasks. We hypothesise that PT-141 nasal spray will increase gaze to the eyes, improve the accurate and fast identification of the correct emotion from faces, and improve the capacity of participants diagnosed with autism to correctly respond to social cues. Positive results will significantly advance the neuroscience of social behavior in this heated research field and develop an exciting new treatment for autism.