In this study, the presence of Campylobacter jejuni in water lines of commercial broiler house and its role in the epidemiology of the infection of broiler flocks was investigated. The study was done in three sequential commercial broiler flocks previously known to be infected with C. jejuni in two poultry houses with different water sources. C. jejuni was identified in drinking water and drinking nipple swab samples in water-line samples from both houses. Fresh fecal dropping samples were taken from broiler flocks for determination of C. jejuni-carriage. Twenty and 130 C. jejuni isolates were recovered from water-line system and fecal dropping samples, respectively. A total of 150 C. jejuni isolates were genotyped by pulsed-field gel electrophoresis (PFGE) with SmaI digestion and 9 distinct PFGE patterns were identified. Six and 5 different PFGE types were identified in houses 1 and 2, respectively. C. jejuni isolates, recovered from water lines samples, were genotypically similar to the isolates from fresh fecal dropping in both houses. These results showed that C. jejuni water-line contamination was related to flock contamination and could help to continuously make it infected with C. jejuni.