The objective of this study was to investigate changes in productivity and behavior useful for illness detection in robot-milked early lactation cows. Production and rumination data were recorded electronically for 6 mo for 605 early lactation cows in 9 commercial herds. Cases of illness were diagnosed and recorded, including retained placenta (RP; n = 58), displaced abomasum (DA; n = 8), mastitis (n = 38), subclinical ketosis (SCK; n = 198), and endometritis (n = 113). Data were summarized by cow, day relative to calving, and day relative to the day of diagnosis for each illness separately, and analyzed in mixed linear regression models. Before calving, daily rumination time of cows that later had an RP started to decline by 11 min/d from −6 to −2 DIM (P = 0.01) and by 41 min/d from −2 to 0 DIM (P < 0.001), whereas cows with no RP only started to ruminate less from −2 to 0 DIM (−44 min/d; P < 0.001). From 0 to 21 DIM, RP cows produced 6.7 kg/d less milk than healthy cows (P = 0.01); milk yield of RP cows increased by 1.15 kg/d (P < 0.001) whereas milk yield of healthy cows increased by 1.24 kg/d (P < 0.001). Accounting for DIM, rumination time declined by 17 min/d from 6 d before DA (P = 0.02) and by 14 min/d from 4 d to mastitis diagnosis (P = 0.006). Milk production dropped by 2.6 kg/d from 5 d before DA (P < 0.001) and by 2.0 kg/d from 3 d before mastitis (P < 0.001). For more chronic disorders (SCK and endometritis), no deviations from baseline occurred before the day of diagnosis, but there were noticeable differences between healthy and sick cows. From 0 to 30 DIM, SCK cows produced 3.5 kg/d more milk than cows without SCK (P < 0.001), but did not spend more time ruminating (P = 0.9). From 0 to 50 DIM, cows with endometritis (diagnosed at 28–35 DIM) produced 4.5 kg/d less milk (P < 0.001) with no difference in rumination time (P = 0.3), but did spend 30 min/d less time ruminating from 0 to 12 DIM (P < 0.001) than cows without endometritis. In summary, acute health disorders, such as RP, DA, and mastitis, were associated with significant deviations in milk yield and rumination behavior 3 to 6 d before diagnosis. More chronic illnesses, such as SCK and endometritis, were associated with substantial, but subtle, longer-term changes in productivity and behavior.