Days open (DO) is considered one of the most important parameters used to determine the reproductive performance in dairy buffalo farms. It is known as the duration between calving and next pregnancy, minimizing this period helps control the calving interval thus reproductive efficiency of the buffalo farms. So, the aim of this study was to apply Poisson regression model to determine factors influencing days open (DO) in dairy buffalo farms, by evaluating several parameters as calving season, parity, 305- day milk production, lactation length, Age at first calving (AFC), age at first service (AFS), calving interval (CI), and evaluate how days open affect the subsequent reproductive indices. A data of 1388 buffaloes were collected from reliable records of large dairy buffalo farms. These buffaloes calved during the period extended from 2003 to 2015. The results of this study revealed that the important factors for DO were uniparous parity (P=0.03), calving season, calving interval, age at first calving, 305-daymilk yield and lactation length (P ≤ 0.001). The reproductive measurements of CI, AFC, and N/C had significant difference at the level of days open groups (P ≤ 0.001). Subsequently; they considered good indicators for evaluation fertility in dairy buffalo farms.