309 samples of raw buffalo's and cow's milk were collected over one year from 3 different milk supplies in Assiut city and examined for microbiological quality .     The microbiological evaluation of milk samples was carried out by the determination of total microbiological counts (T.M.C), presence of coliform bacteria (CB), and estimation the incidence of both aerobic spores(AS) and anaerobic spores bacteria ( ANAS ).     Generally, the average (T.M.C) of investigated milk samples was 8.94 x10¹² C.F.U /ml. The higher microbiological count was detected in cow's milk samples ( 1.09x10¹³ ) as compared with buffalo's milk samples ( 5.54x10¹² ). In addition , samples collected during cold months appeared to have lower  microbiological counts ( 1.40 x10⁷ )than that during warm months ( 1.39 x10¹³ ) .     The average (CB) titer was 3.16 x 10⁴ bacterium /ml . Samples of cow's milk showed lower (CB) titter ( 2.06x 10³ /ml) than those of buffalo's milk    ( 8.21 x10⁴/ml ). Furthermore, high incidence of (CB) was found in samples collected during warm months (4.3 x10⁴/ml) . The (CB) titer of cold months samples was (1.15.x10⁴ /ml ) .     The mean value of (AS) incidence was 2.21 x 10³ /ml. The incidence of (AS) was high in buffalo's milk (3.25 x10³ ) than in cow's one 1.6 x10³ /ml . Samples collected during cold months appeared contaminated with (AS) in cow level ( 1.2 x10³ spores /ml ) than that found in warm months samples    ( 2.77 x 10³ ) .     The mean value of (ANAS) incidence was 26.4 spores /ml. Buffalo's milk contained  (ANAS) with high level (39.7) than cow's milk (18.6 spore /ml) .Samples collected during cold months showed low incidence of ANAS (9 spores /ml ) compare with 46 spores /ml in samples of warm months.