A report is presented of the effects upon the liver and enteric mucosa of rats treated chronically with azathioprine (AZA) and cyclophosphamide (CY) in equiactive doses three times greater. The groups treated either with equiactive doses of AZA and CY or with doses three times greater of AZA and CY presented limited and moderate morphological alteration in the liver and in the mucosa of the small intestine, while all rats treated with high dose of CY died in the first phase of the experiment.