This study was conducted to evaluate the pathological changes in broilers fed a diet containing low-levels of aflatoxin (AF) and clinoptilolite (CLI) until 42 days of age. A total of 576 one-day-old Ross-308 type broiler chicks were treated with varying levels of AF and CLI (15 g kg(-1)). The gross and histopathological changes in the liver, kidneys, spleen, thymus and bursa of Fabricius were investigated and relative organ weights were calculated. Compared to controls, significant changes (P<0.05), such as slight to moderate hydropic degeneration and/or fatty change (8 cases of 10), bile-duct hyperplasia (7 of 10) and periportal fibrosis (5 of 10), were found in chicks fed 100 ppb AF-containing diet. No gross-pathological changes were observed in any treatments. The addition of CLI to the 100 ppb AF-containing diet significantly decreased the number of affected broilers and/or the severity of lesions (hydropic degeneration and bile-duct hyperplasia) in the livers (P<0.05). The addition of CLI to the AF-free diet did not produce any significant lesions compared with the controls.