The sleeper block unit (1) for railway track systems consists of a sleeper block (2) and of a sleeper shoe (3) that partly surrounds the sleeper block (2). The sleeper block (2) has a head portion (4) and a base portion (6), the head portion (4) extending beyond the base portion (6) in length and in width, thus forming a step (10). At the upper edge of the sleeper shoe (3), a surrounding, upwardly and outwardly extending sealing lip (14) that lies against the step (10) is arranged. As a result, during vertical movements of the sleeper block (2) in the sleeper shoe (3), the sealing lip (14) is deformed substantially vertically in the elastic range rather than rubbing against an outer wall of the sleeper block as in known sleeper block units. In this manner the sealing lip is subject to reduced wear so that the sealing effect is maintained for a longer period and the sleeper block unit (1) has a longer lifetime.