BACKGROUND: Melatonin's antioxidative and immune effects suggest potential in cancer therapy. This review assesses related clinical trials on ClinicalTrials.gov. METHODS: All ClinicalTrials.gov trials registered up to January 17, 2024 were examined, focusing on trials that involved use of melatonin in cancer treatment. A 46 trials were summarized by their study status, study phase, study type, funder type and study results in the use of melatonin in cancer treatment. RESULTS: The examination of the research data revealed a collective count of 46 clinical trials enlisted on ClinicalTrials.gov, all focus around the utilization of melatonin in cancer treatment. Among these, 24 trials had reached completion, constituting 91.3% of the entire trials, while 5 trials were presently in the recruitment phase, making up 10.8% of the total. None of these trials had received approval for marketing yet. The majority focus of the analysis encompassed interventional studies, around 42 trials and representing 91.3% of the overall trials, thereby incorporating most enrolled patients. In contrast, observational studies are a smaller fraction, comprising 4 trials (8.6% of the total), with a correspondingly lower number of involved patients. Regarding funding sources, most registered studies secured funding from diverse entities such as individuals, universities, and organizations, constituting 95.6% of all trials. In comparison, a minority of studies received funding from the National Institutes of Health, comprising 5 trials and accounting for 10.8% of the total trials. CONCLUSION: The analysis of 46 clinical trials on melatonin's use in cancer treatment reveals a significant importance on interventional studies. Overall, these findings contribute to the evolving understanding of melatonin's role in cancer treatment.