This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP), a known ethylene action inhibitor, on fruit quality and incidence of physiological disorders during a simulated marketing period in new mid-season Asian pear (Pyrus pyrifolia Nakai) ‘Changjo’. Flesh firmness of untreated control fruits was maintained with a hardness of 20.2 N until day 14 of simulated marketing but decreased rapidly to 6.2 N at day 21 of simulated marketing; losing its commercial quality. However, the firmness of 1-MCP treated fruits remained high (> 20.7 N) during the same period. Quality indices such as soluble solids content and titratable acidity in ‘Changjo’ pear did not show any significant differences during simulated marketing period regardless of 1-MCP treatment. For the difference in skin color, redness (a*) tended to increase as simulated marketing period became longer, and 1-MCP treatment delayed this change by 7 days compared to the untreated fruits. No decrease occurred in ethylene production level with 1-MCP treatment in ‘Changjo’ pear. Meanwhile, 1-MCP treated pears showed a significantly lower respiration rate compared to the untreated fruits. Also, 1-MCP treatment effectively reduced the incidence of physiological disorders including internal flesh browning and mealiness symptoms during simulated marketing periods of 21 and 14 days, respectively. Therefore, we conclude that the use of 1-MCP is recommended for quality maintenance and for prevention of physiological disorders during simulated marketing periods of ≥ 7 days for mid-season Asian pear ‘Changjo’.