Changes in rumination time (RT) can be used as an indicator of illness, yet no work to date has evaluated this relationship in dairy cows on pasture. The objectives of this study were to describe the RT of grazing dairy cows during the transition period and to determine the relationship between metritis and RT. Our sample included 53 multiparous and 17 primiparous Holstein cows that calved during the spring season at the Experimental Dairy Farm of the Universidad Austral de Chile (Valdivia, Chile). Cows were assessed every 2 or 3 d between 3 and 21 d in milk, and metritis was diagnosed by inspection of the vaginal discharge. Any presence of other clinical disease was recorded, and cows were subsequently categorized into 2 health categories: (1) healthy, no metritis and had no other signs of clinical (retained placenta, milk fever, metritis, mastitis) postpartum diseases; and (2) metritis, diagnosed as having metritis with no other signs of clinical postpartum disease with the exception of retained placenta. RT was recorded daily using an automated monitoring system from 3 wk before calving to 3 wk after calving. Data were analyzed using mixed linear models (SAS v9.4). The RT differed between healthy primiparous and multiparous cows; primiparous cows had lower RT during the precalving (d −21 to d −2; 504 ± 41 min/d vs. 559 ± 19 min/d; P < 0.001) and postcalving period (d 2 to d 21; 423 ± 9 min/d vs. 483 ± 5 min/d; P < 0.001) compared with multiparous cows, but RT did not differ between these parity classes at calving (d −1 to d 1; 412 ± 33 min/d vs. 426 ± 18 min/d; P = 0.60). The average number of days from calving to the first signs of metritis was 7.5 ± 0.7 d for primiparous cows and 6.7 ± 0.6 d for multiparous cows. A health status × day interaction was seen for the RT in primiparous cows (P = 0.02), but not for multiparous cows (P = 0.95) during d 3 to d 7 after calving. Primiparous cows that developed metritis spent less time ruminating (P < 0.05) during d 6 and d 7 compared with healthy cows. Our results suggest that changes in RT is not a good early indicator of metritis but is affected when the disease is already present in grazing dairy cows. Project funded by FONDECYT #11170820.