This study was done to determine the enterotoxin of E. coli using polymerase chain reaction technique (PCR). One hundred and twenty samples (20 raw milk, 15 zabady, 15 ice cream , 10 kariesh cheese ,10 soft cheese, 15 sausage, 15 luncheon and 20 faecal calves diarrhea) were collected from different localities in Kaluobia Governorate and examined for the occurrence of pathogenic and toxigenic E.coli. E. coli was isolated at a higher percentage from kariesh cheese (66.3%) followed by faecal sample and zabady (50%), raw milk (41.6%) sausage (40%), ice cream (36.3%), luncheon (25%) and at a lower percentage from soft cheese (20%). E. coli could be isolated onto Sorbitol MacConkey agar media (SMA) and Eosin methylene blue agar media (EMB) as method for recovery of the pathogenic E.coli which were isolated in percentages of 44.4% and 48.8% respectively. Serological typing of the isolated E.coli strains (12 isolates randomly selected) using specific (O) antisera, revealed the identification of different (11) serotypes (Olll, O86A, O124, O146, O158, O8, 078, O18, O25, O114, O148). By using polymerase chain reaction technique' (PCR) for detecting enterotoxins encoding genes for shiga like toxin (STx) and effacing attaching primer (eae), the results revealed that toxigenic E.coli encoding eae gene was detected in 6 out of 8 randomly chosed E.coli isolates ,while shiga like toxins was found in 4 out of the same 8 randomly E.coli isolates . In conclusion E.coli was the most common bacterial pathogen isolated from examined diarrhea of diseased calves and the main common E.coli serovars associated with food poisoning cases and diarrhea in calves were O111, O158, O86a, O124, O25, O18, O8, O124 and O146. From identification using PCR found that enterotoxigenic E.coli were common than shiga toxigenic E.coli.