Abstract THROUGH the courtesy of 22 poultry departments at various state experiment stations, this study of the incidence of gizzard erosion was made possible. Fifty to seventy-five eggs were furnished, gratis, by these departments, shipped to Durham, New Hampshire, and all hatched out in one incubator under identical conditions. Sixty-eight eggs each from two typical pens of New Hampshires from the college flock were also included. These eggs were set on May 23, 1940, hatching June 13, 1940, with the exception of two lots that arrived later and hatched on June 17, 1940. As may be noted from Table 1, a total of 715 chicks hatched, or 53.6 percent of total eggs set. It should be borne in mind that these eggs were shipped in many cases from long distances; also in one or two cases that poor fertility and damage in transit caused poor hatching results. These chicks were all . . .