Plasma samples from dairy cows across two seasons (warm and cold) were re-assayed utilizing a more sensitive and uniform procedure in order to assess the use of progesterone and PGFM concentrations on the day of AI (Day 0) to day 8 in predicting future pregnancy status of the cow (pregnant vs. open, maintenance vs. loss of pregnancy). The effect of season on progesterone and PGFM serum levels was also assessed. Progesterone concentrations on the day of AI did not differ between cows inseminated during different seasons, nor did they differ between cows of different pregnancy statuses. PGFM concentrations on the day of AI also did not display any differences in cows of various pregnancy statuses, but there appeared to be a seasonal effect, with cold season cows maintaining higher PGFM levels than warm season cows. These results were unexpected, but do suggest that PGFM and progesterone levels on the day of AI may not be the best predictive factor for establishment of pregnancy.