Glutathione content increased during the reproductive period and decreased thereafter up to the 43rd day of age in whole body as well as mitochondrial homogenates of ageing Zaprionus paravittiger. However, females exhibited higher levels of glutathione as compared to males. In whole body homogenates, propyl gallate (PG; 25 micrograms/ml) increased the glutathione content significantly up to the 22nd day of life whereas in mitochondria it increased during all age intervals in the two sexes with the exception of the 36th and 43rd day of survival in males. In conclusion, the higher level of glutathione on PG feeding might be one of the factors leading to the prolonged life span of flies.