Major predisposition of dairy cattle to disease and shown low reproductive performance occurs during the first weeks of lactation. With the objective of determine the incidence of early postpartum diseases and their effect on the increase of the conception interval, a longitudinal cohort study was carried out in cows (n = 706) of dairy production systems in the municipality of Pasto, Colombia. Follow-up was performed during the first 45 days postpartum in 47 herds to determine the presence of postpartum disease, and monthly follow-ups were performed for gestation diagnosis. The effect of exposure to disease in the early postpartum period on the increase of open days was established through logistic regression. In the study, the diseases that contribute significantly to the increase of calving - conception interval to a number greater than 120 days were: pneumonia (p-value=0.001; OR=4.2); Clinical mastitis (p-value=0.001; OR=7.3); Metritis (p-value=0.014, OR=48.1); Placenta retention (p-value=0.001; OR=17.07); Cardiac alteration (p-value=0.0001, OR=2.9) and lameness (p-value=0.014; OR=2,9). The study allowed to conclude that occurrence of early postpartum disease has an effect on the increase of open days with calving – conception intervals greater than 120 days. Occurrence of disease during early postpartum can predict the probability of occurrence of low reproductive performance.