The enterochromaffin cells of the gastrointestinal (GI) tract secrete 400 times as much melatonin as the pineal gland; therefore, it is not surprising that research is finding that this indole plays an important role in GI functioning. In animal studies, it protects against GI ulcerations, and randomized clinical trials suggest its efficacy in treating functional dyspepsia and irritable bowel syndrome. Melatonin administration has been shown to protect against esophageal lesions in animals. Moreover, in a randomized, single-blind clinical trial of subjects with gastroesophageal reflux disease (GERD), the combination of melatonin with other natural supplements was found to be superior to omeprazole, a proton pump inhibitor (PPI). Its administration as a single treatment for GERD has not been previously reported. A 64-year-old Caucasian female who required treatment with a PPI for symptoms of GERD wished to substitute a natural treatment because of the risk of worsening her osteoporosis. She experienced a return of symptoms following each of three 20-day trials of a proprietary blend of D-limonene when attempts were made to discontinue the PPI. She then underwent a trial of a natural formula consisting of melatonin 6 mg, 5-hydroxytryptophan 100 mg, D,L-methionine 500 mg, betaine 100 mg, L-taurine 50 mg, riboflavin 1.7 mg, vitamin B6 0.8 mg, folic acid 400 microg, and calcium 50 mg. After 40 days, the PPI was withdrawn without a return of symptoms. Subsequently, an attempt to reduce melatonin to 3 mg resulted in symptoms, while all other ingredients were withdrawn with minimal symptoms during 10 months of follow-up.