A survey of 516 English sparrows from 25 states was made and data were accumulated concerning the seasonal and geographic distr. and the incidence of infection with P. elongatum, P. cathemerium and P. relictum. The last was present in 31 of the birds, P. cathemerium 5, and P. elongatum in 4; 18 were unidentified as to sp. The monthly incidence of infection was quite low with the beginning of winter and sparrows captured during Jan. and Feb. were completely parasite-free. Following a very low incidence in March, the level of infection rose and in general remained high during the spring and summer months. 11% of the birds in this study were infected with malarial parasites.