The independence of stage and grade as prognostic factors for prostatic carcinoma is unclear. Previous studies have been hampered by both the uncertain reproducibility of subjective grading systems and the lack of a scalar grading measure, and have reached opposing conclusions. To examine this question, we quantitated via point-counting the per cent of tumor cells showing glandular differentiation in 90 cases of primary prostatic adenocarcinoma. Patient records were examined retrospectively to verify both the stage at presentation and follow-up. Stage and morphometric grade were found to be inversely correlated, (p less than 0.001), with the mean per cent of tumor cells showing glandular differentiation at each stage as follows: A--71 per cent; B--59 per cent; C--33 per cent; D--28 per cent. Analysis of variance revealed these differences to be significant (p less than 0.001), and Newman-Keuls test showed significant differences between the following stage pairs: A-C, A-D, B-C, B-D (p less than 0.05). In spite of the marked correlation between stage and grade, multiple regression analysis showed them to be independent predictors of survival, although their combined effect was not much greater than that of morphometric grading alone. We conclude that, for prostatic carcinoma, the close correlation of stage and grade makes it difficult to combine them in determining the prognosis of the individual patient, although both together may be useful in studies of large populations.