The objective of the study was to determine the prevalence of E coli carrying the gene encoding ESBLs in patients with common diseases visiting primary health care centres in 8 provinces of the Northern region (Ha Noi, Ha Nam, Hai Duong, Bac Ninh), the Central region (Thua Thien - Hue, Khanh Hoa), and the Southern region (Can Tho, Ben Tre) of Vietnam.