As an alternative to the standard Draize eye irritation test, the potential irritancy of compounds was evaluated by observing adverse changes that occur in chorioallantoic membrane CAM) of the hen egg (HECAM) after exposure to a test chemical placed directly on the CAM. The occurrence of hemorrhage, coagulation, and lysis in response to a test compound is the basis for employing this technique to evaluate its potential for in vivo damage to mucous membrane, in particular the eye. Irritancy is scored according to the severity and speed at which damage occurs. In the present study, five different classes of pesticides were screened for irritation potential. There was good correlation between the HECAM assay and the in vivo Draize eye irritation test. The proposed HECAM assay, which reduces the requirement for laboratory animals, could be a painless alternative to the Draize test.