We propose to evaluate the usefulness of computer-assisted morphometric analysis (CAMA) in defining late radiation effect and selected chemotherapeutic alterations in the kidney. Subjective histologic grading allows reasonably reproducible assessment of late renal radiation effects, but quantitation of renal tubular and glomerular radiation sequelae needs to be improved in order to lessen observer bias, and to detect damage earlier and after smaller radiation doses. The CAMA method uses nuclear size, total chromatin density and chromatin texture variation for inter-cellular comparisons, measures which seem especially applicable for evaluation of long-term damage. We propose to determine: (1) Sensitivity and precision of CAMA in defining radiation response. (2) Correlation of CAMA changes with histopathologist assessment. (3) Whether the effect of a given dose increases with time. (4) Relative biological effectiveness of single dose, 5 and 15 fraction x-ray and pion exposures in eliciting radiation response. (5) Whether the effect of selected radiation sensitizer or protector agents can be demonstrated. (6) The usefulness of CAMA in quantitation of cis-platinum renal toxicity and the protective effect of WR 2721 against such toxicity.