Background Hyporexia and weight loss are important indicators of physical and psychological well‐being in macaque colonies. An FDA‐approved transdermal formulated Mirtazapine (MTZ) shows effectiveness in managing feline hyporexia. This study sought to determine its effectiveness as an appetite stimulant in macaques. Methods Fourteen macaques with idiopathic hyporexia, intractable to conventional management were treated with transdermal MTZ (0.5 mg/kg) topically administered to aural pinnae once daily for 14 days. Qualitative food consumption was monitored daily for 6 months. Body weights were collected prior to treatment, every 2 weeks for the first 6 weeks, 10 weeks, and 6 months post‐treatment. Results Transdermal MTZ significantly reduced the frequency of hyporexia during treatment and monthly for 6 months. No significant increase in weight noted until approximately 6 months post‐treatment. Conclusions Results from this study indicate that a short course of transdermal MTZ is an effective way to increase food consumption in macaques chronically.