Abstract: Diarrhea is one of the leading causes of illnesses and death among children in developing countries, where an estimated 1.3 billion episodes and 4-10 million deaths occur each year in children below 5 years of age. Escherichia coli strains are among the major bacterial causes of diarrheal illness. There are now 7 classes of diarrheagenic E. coli, namely enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), diarrhea-associated hemolytic E. coli (DHEC) and cytolethal distending toxin (CDT)-producing E. coli. Due to the need for costly and labor-intensive diagnostic procedures, identification of diarrheagenic E. coli (DEC) is difficult at standard laboratories. Therefore, the epidemiology of DEC infections remains an important issues particularly developing country. Recently, Polymerase Chain Reaction (PCR) or dot blot has been used for genetic detection of DEC. In this study, we analyzed 25 E. coli isolates from different sources in Malaysia. Using primers for 671 bp gad gene successfully amplified by PCR. Dot blot analysis for high-throughput, rapid, simple and inexpensive quantification of specific microbial populations was evaluated and used to confirm the results of PCR. The protocol of the assays is readily applicable for implementation in the food processing, water quality control and clinical diagnosis.