Enteritis is most fatal disease especially for neonatal and young buffalo calves. Out of 150 fecal samples, 100 from diarrheic and 50 from non diarrheic (apparently healthy) buffalo calves were collected from private farms for isolation and identification of E.coli using morphological, cultural, biochemical and serological examination. Further cytochemical enzyme characterization of the different identified serogroups were carried out through the cytochemical quantitative determination of bacterial mitochondrial Adenosene-tri phosphatase (ATP-ase) and succinic dehydrogenase (SDH-ase) enzyme activities for their possible variations among the isolated and identified E.coli serogroups. Four values to each of E.coli serogroup (2 for each enzyme) as optical densities (OD.) could be obtained : (ATP-ase activity & Actual ATP-ase reaction and SDH-ase activity & Actual SDH-ase reaction) for E.coli-serogroups: E.coli O₂₆, E.coli O₅₅, E.coli O₇₈, E.coli O₈₆ and E.coli O₁₁₁ as following: (0.595 & 0.285 and 0.560 & 0.210), (0.565 & 0.265 and 0.550 & 0.200), (0.590 & 0.255 and 0.540 & 0.190), (0.590 & 0.205 and 0.490 & 0.180) and (0.600 & 0.160 and 0.560 & 0.150) nm respectively. It was observed that the SDH-ase enzyme activity differentiate between the majority of the studied E.coli-serogroups for the significant (P≤0.05) variations between their enzyme activities (except between the serogroups E.coli O₂₆ and E.coli O₁₁₁ which showed the same (non-significant) SDH-ase activity, but ATP-ase enzyme activity could not differentiate between the different E.coli serogroups because of its non-significant variations among different serogroups (except with the serogroup E.coli O₅₅ which showed the significant lower ATP-ase enzyme activity and noted to be lower pathogenic than the other E.coli serogroups), so that the actual ATP-ase enzyme activities (the difference between the OD. after and before incubation period) may be used for differentiation between different serogroups. Further cytochemical characterization to other bacterial enzymes and to other E.coli serogroups should be carried out as additional tool for a definite differentiation and characterization of E.coli serogroups causing enteritis in buffalo calves.