Experiments were conducted to test the ability of chitin or chitosan to control anthracnose (Colletotrichum sp.) on cucumber (Cucumis sativus L.). Practical grade chitin and unpurified chitin (ground crab shells) were added to compost at concentrations of 0.05 and 0.1% and chitosan was applied to the leaves of the plant at the concentrations of 0.05 and 0.1%. A fungicide (penncozeb) was used as a positive control while water and untreated plants were used as negative controls. Conidia of Colletotrichum sp. were applied to all the plants to initiate even disease development. All three treatments of chitin, at various concentrations, resulted in control of Colletotrichum sp. that was comparable to the fungicide. These results showed that Colletotrichum sp. on cucumber could be controlled by the use of chitin or chitosan and that both gave comparable levels of control.