We consider the impact of job rotation in a directed search model in which firm sizes are endogenously determined and match quality is initially unknown. A large firm benefits from the opportunity of rotating workers so as to partially overcome loss of mismatch. As a result, in the unique symmetric equilibrium, large firms have higher labor productivity and lower separation rates. In contrast to the standard directed search model with multi-vacancy
firms, this model can generate a positive correlation between firm size and wage without introducing any ex ante productivity differences or imposing any non-concave production function assumption.