Postpartum uterine infections have been associated with reduced fertility in dairy cows; however, the mechanism by which uterine infections limit reproductive function has not been clearly determined. The purpose of this study was to elucidate the relationship between uterine infections in the early puerperium and the onset of folliculogenesis in dairy cows. The pattern and intensity of uterine infections and follicular dynamics were studied in cows that shed fetal membranes (n = 18), and in those that retained fetal membranes after parturition (n = 18). Endometrial swabs collected aseptically from each animal on Days 4, 8 and 12 after parturition were cultured. Ultrasound scanning of the ovaries was carried out on Days 4, B and 12 using a B mode, real-time, linear array ultrasound scanner. The total number of follicles was recorded, and the follicles were classified according to size as small (2 to 4 mm) or medium (5 to 7 mm). The severity of infection was higher (P<0.05) in retained placenta cows on Days 4, 8 and 12 compared to nonretained placenta cows. The total number of follicles was larger (P<0.05) in nonretained placenta cows on Days 4, 8 and 12 than in retained placenta cows. The distribution of different sizes of follicles on all days of observations was similar in both groups of cows (P>0.05). These data support the hypothesis that uterine infection may delay the initiation of folliculogenesis and suppress the rate of follicular growth in dairy cows in the immediate postpartum period.