Studies of a Maryland population of marked box-turtles (Terrapene carolina) in 1945, 1955, 1965 and 1975 showed a pronounced decline in population size during the three decades; the greatest change came between 1965 and 1975, when numbers were reduced by half. Proportions of females and of young also declined. Fifteen % of the males and 11% of the females that were more than 20 years old in 1945 still were present in 1975; some probably were more than 80 years old.