The Browns' playoff history is 17-21 and includes 8 titles. The first four were the All America Conference in the late 40's. For those who think that was a minor league, the validity of those titles was established by the Browns' entry into the NFL in 1950 when the Browns, 49ers and Colts merged with the NFL. In their first game, the Browns obliterated the defending NFL champ, the Eagles, 35-10 (Otto Graham, Marion Motley, Bill Willis, Len Ford vs. Norm Van Brocklin and Steve Van Buren) before 71,000 in Philadelphia. They beat the Eagles again later that season and then went onto win the NFL championship that year on a Lou Groza field goal, beating the now LA Rams, 30-28.
The Browns were, by far, the best team in pro football for a decade (1945-1955). They last won a title (over the Unitas-led Colts) in 1964. There were the Sipe years and the Bernie years in the 80's, but mostly a lack of success since PB left.