Bitter melon or Dong du (Momordica charantia Linn) that was grown in the spring-summer in ancient alluvial soil was used for this study. The physiological and biochemical changes of bitter melon fruits were studied at different times (5, 10, 15, 20, 25, 30 and 35 days old). The research results showed that the size, volume and weight of bitter melon fruits were greatest when 30 days old, and yet after that they slowly increased in size and weight. The pigment content in the fruit changed over time. The Chlorophyll content increased rapidly from 10 to 20 days of age and then the increase slowed gradually. Chlorophyll b content in the fruit was always higher than chlorophyll a. However, the carotenoid content was low during first 30 days old and then rapidly increased when the fruits ripened. This explains why color of the peel color is age dependent. The maximum concentration of organic acids and vitamin C in bitter melon fruit, 33.898 Idl/100 g and 47.75 mg/100 g, respectively, was found in 30-day old fruit.