The population dynamics of Mediterranean fruit fly (MFF), Ceatitis capitata (tared.) and peach fruit fly (OFF), Bactrooera zonata (Saund.) was studied in peach, guava and fig orchards at Sinuris and Ibshaway districts, Fayoum Governorate, during the two successive seasons 2003 and 2004. In the same time, rate of infestation in peach, guava and fig fruits with MFF and PFF together and separately were estimated. During the two successive seasons, MFF population was low compared with PFF population. During the 1st season, captured per trap per day "CTD" for MFF ranged between 0.1-8.4 flies with mean of 1S1 flies in peach orchards, 0.14-0.61 fly with mean of 0.33 fly In guava orchards, and 0.0 - 0.24 fly with mean of 0.07 fly in fig orchards. During the 2nd season, the respective "CID" for MFF ranged between 0.0 - 8.57 flies with mean of 3.62 flies, 0.0 - 0.14 fly with mean of 0.02 fly, and 0.0 - 0.14 fly with mean of 0.02 fly in peach, guava and fig orchards. The "CTD" of PFF ranged between 12.2-107.3 flies with mean of 34.21 flies; 7.14 - 54.29 flies with mean of 19.87 flies in peach orchards; 28.57 - 60.72 flies with mean of 50.90 flies; 8.4837.95 flies with mean of 20.45 flies in guava orchards; and 0.016.67 flies with mean of 8.28 flies; 0.12 - 27.43 flies with mean of 8.44 flies in fig orchards during the two successive seasons, respectively. During the 1" season, the total percentage of infest ation with MFF and PFF together reached 29.24, 49.54 and 3.37 % in peach, guava and fig, respectively. During the 2nd season, the total percentage of infest ation with MFF and PFF together reached 36.91 % in peach, 41.13 % in guava and 2.75 % in fig. During the 1" season, percentages of infest ation with MFF was 15.23, 0.02 and 0.12 % in peach, guava and fig, respectively. During the rd season, percentages of infestation with MFF was 10.99 % in peach, 0.11 % in guava and 0.19 % in fig. Percentages of infestation with PFF during the 1st and r° seasons were 14.01, 49.52 and 3.25 %, and 25.92 and 41.02 and 3.56 % in peach, guava and fig, respectively.