Psammaplin A and pentoxifylline, two chitinolytic enzyme inhibitors, were evaluated for their palatability, feeding deterrence, consumption, and subsequent mortality against the eastern subterranean termite, Reticulitermes flavipes (Kollar). Psammaplin A and pentoxifylline were incorporated into filter paper diets at 0.0375, 0.075, 0.15, and 0.3%, and 0.01, 0.02, 0.04, 0.08, and 0.21% active ingredient (w/w), respectively. The treated filter papers served as food source or bait for termite workers used in this study. No-choice and two-choice feeding bioassays assessed bait consumption, palatability, repellency, and biological activity over a period of 1 - 5 wk (no-choice assay) and 3 - 5 wk (two-choice assay) of feeding. Neither psammaplin A nor pentoxifylline treatment repelled eastern subterranean termite diet consumption (in both nochoice and two-choice feeding arenas) as feeding commenced on both diet types within 48 h. In no-choice feeding tests, diet consumption was significantly decreased in termites fed 0.3% (2 - 5 wk) and 0.15% (4 - 5 wk) psammaplin A treated diet. Pentoxifylline treatment decreased diet consumption at 0.21% (3 wk). Consumption ratio trends suggest increased diet consumption rates by survivors feeding on chitinase inhibitor treated diet. In two-choice tests, termites consumed almost equal amount of diet treated with psammaplin A or pentoxifylline and untreated diet (with the exception of diet treated with 0.3% psammaplin A). Under no-choice bioassays, termite mortality from all concentrations of both chitinase inhibitor treated diets was significantly greater than that from untreated diet. Biological activity of psammaplin A and pentoxifylline treated diets in 2-choice feeding arenas was reduced by greater than 50% in comparison with no-choice feeding arenas. These results indicate the novel potential of chitinase inhibitors as effective active ingredients for a termite baiting program.