The objective was to assess the effect of eCG administration on d 7 postpartum (pp) on ovarian cyclicity, uterine health and uterine involution in lactating dairy cows. Healthy cows [n = 34, 21 primiparous (PR) and 13 multiparous (MP)] were enrolled in the study. Cows were stratified by parity and BCS, and randomly assigned to receive either 500IU eCG (n = 16) or 2mL 0.9 saline (control = 18) on d 7 pp by IM injection. Ovaries were examined by transrectal ultrasound (US) from d 10 pp until ovulation or regression of the first follicle wave; the diameter of the dominant follicle was recorded at each exam.US exams were conducted on d 21, 28, 35 and 42 pp to measure the diameter of the cervix and the uterine horns. Vaginal discharge score was recorded on a 1 to 5 scale on d 14, 21, 28, 35 and 42 pp. Endometrial cytology samples were collected on d 42 pp, and the percentage of polymorphonuclear leukocytes determined. Milk samples were collected 3 times per week from d 14 pp until d 60 pp for progesterone determination. All data were analyzed using mixed models in SAS. The model included treatment and lactation as fixed effects and cow as a random effect. Treatment did not affect ovulation of the first follicle wave (10/16) vs. (11/18), days to commencement of luteal activity (CLA) (22.6 vs 22.0 d), duration of the first luteal phase (11.9 vs. 11.4 d) or incidence of subclinical endometritis (3/16 vs 1/18) in eCG vs Control cows, respectively. An interaction between treatment and parity was detected for CLA (P = 0.03), whereby CLA was shorter for MP eCG cows (21.0 d) compared with MP Control cows (28.4 d), but was not different in PR cows(21.5 vs 21.0 d). There were no effects of treatment on uterine involution or clinical endometritis. Overall, eCG treatment on d 7 pp had little effect on the reproductive tract measurements collected.