Medlar (Mespilus germanica L.) is grown wildly in the Talesh city of Guilan province (Iran) and is considered a popular fruit that is harvested in November and December. Hydrogen sulfide (H2S) was recently recognized as an endogenous gaseous molecule that delays senescence in plants. This study was conducted to determine the effects of postharvest application of H2S fumigation released from 0 (control), 0.5, 1, and 1.5 mM H2S donor NaHS on some of the qualitative parameters of medlar fruit during 0, 7, 14 and 21 days of shelf-life at room temperature (21-25 degrees C). On the sampling dates, firmness, soluble solid content (SSC), titratable acidity (TA), pH, and skin browning index of fruits were analysed. The experiment was conducted in a factorial experiment based on a completely randomized design with three replications. According to the results, medlar fruit treated with 1 mM NaHS had the lowest SSC, the highest TA, and fewer pH by the end of shelf-life. Moreover, 1 mM NaHS treatment, as an H2S donor, maintained higher fruit firmness. Also, our results revealed that the skin browning index of the treated medlar fruit with 1 mM NaHS was reduced compared to other treatments throughout 21 days of shelf-life. In general, it can be concluded that 1 mM NaHS treatment was the most effective treatment for maintaining the quality of medlar fruit during the shelf-life.