Fowl paralysis is generally considered to be a disease of birds over three months of age. In the present paper data are presented on 45 out of 244 chicks (18.4%), which developed clinical symptoms of fowl paralysis before 90 days of age. Of these, 20 were inoculated and 25 were not inoculated. Forty-two of the 45 chicks (93.3%) showed lesions in the nervous system. Nine chicks (20%) showed lymphomatous tumors.Seventeen of the 45 cases (37.7%) occurred in chicks less than 60 days of age; the same number of cases occurred between 60 and 74 days of age; and 11 cases (24.4%) occurred between 75 and 89 days of age. The mean age of all chicks that developed paralysis was 64.4 days.The fact that typical fowl paralysis occurred in one chick at 37 days, and in several from 40 to 44 days of age, would indicate that the disease may develop at a very rapid rate.