The distribution, directionality and motility of the actin fibers control cell shape, affect cell function and are different in cancer versus normal cells. Quantification of actin structural changes is important for further understanding differences between cell types and for elucidation of the effects and dynamics of drug interactions. We have developed an image analysis framework for quantifying F-actin organization patterns in confocal microscope images in response to different candidate pharmaceutical treatments. The main problem solved was to determine which quantitative features to compute from the images that both capture the visually-observed F-actin patterns and correlate with predicted biological outcomes. The resultant numerical features were effective to quantitatively profile the changes in the spatial distribution of F-actin and facilitate the comparison of different pharmaceuticals. The validation for the segmentation was done through visual inspection and correlation to expected biological outcomes. This is the first study quantifying different structural formations of the same protein in intact cells. Preliminary results show uniquely significant increases in cortical F-actin to stress fiber ratio for increasing doses of OSW-1 and Schweinfurthin A(SA) and a less marked increase for cephalostatin 1 derivative (ceph). This increase was not observed for the actin inhibitors: cytochalasin B (cytoB) and Y-27632 (Y). Ongoing studies are further validating the algorithms, elucidating the underlying molecular pathways and will utilize the algorithms for understanding the kinetics of the F-actin changes. Since many anti-cancer drugs target the cytoskeleton, we believe that the quantitative image analysis method reported here will have broad applications to understanding the mechanisms of action of candidate pharmaceuticals.