The population dynamics of Mediterranean fruit fly (MFF), Ceratitis capitate (Wied.) and Peach fruit fly (PFF), Bactrocera zonate (Saund.) were studied in mango orchards at Sinuris and Ibshaway districts, Fayoum Govemorate (Egypt) during the two successive seasons, 2002 and 2003. In the meantime, rate of infestation in mango fruits with MFF and PFF together and separately were estimated in six locations. During the two successive seasons, MFF was very low compared to PFF population. Captured per bap per day "CTD" of MFF ranged between 0.09 -0.81 fly, with a mean of 0.26 fly, nd between 0.09 - 1.59 flies, with a mean of 0.57 fly, during the two successive seasons, respectively. The "CTD" of PFF ranged between 59.5 - 275.0 flies, with a mean of 129.49 flies and between 21.97 - 147.32 flies, with a mean of 95.79 flies, during the two successive seasons, respectively. Total percentages of infestation with MFF and PFF together at the six locations, during the 1st season ranged between 4.78 - 27.15 ⁰/0, with a mean of 18.20 %. Percentages of infestation with MFF separately were zero % (because no any MFF was emerged from incubated mango fruits), and percentages of infestation with PFF were the same total percentages of infestation. During the 2 nd season, total percentages of infestation with MFF and PFF together ranged between 8.75 % - 16.76 % with a mean of 13.17 %. Percentages of infestation with MFF ranged between 0.10 % -0.34% with a mean of 0.16 %, and percentages of infestation with PFF ranged between 8.65 % - 16.65 % with a mean of 13.01 %.