Rabe K, et al. - One-hundred consecutive cases of invasive, stage II carcinomas were independently graded twice, with an intervening 4-week intervening wash-out period, by six breast pathologists using established Nottingham grading criteria in order to evaluate the degree of interobserver agreement for invasive carcinoma grade among pathologists and ascertain its impact on pathologic prognostic stage. Interobserver variability varied from good to very good along with even superior intra-observer variability. The most reproducible component was tubule score. In rounds 1 and 2, complete concordance was attained in 54 cases and 58 cases, respectively. In round 1, in only 25 of discordant cases, 18 of which were stage IA vs IB, this led in distinct pathologic prognostic stage. In summary, between pathologists,grading agreement was good to very good and discordant grades led to minute variations to pathologic prognostic stage.