As PT floor slabs become thinner, a doubt about its vibration behavior and comfort of occupants arises. This paper investigates several approaches for determining the post-tensioned slabs behavior for human induced vibrations which can give a high accuracy for determining the vibration behavior and can be considered as a simple tools and a guide for designers. It also studies the vibration behavior of slabs with different span length, and thicknesses and relates vibration response to natural frequency of floor. The results show that the frequency of the slab is increased by decreasing the span length or increasing the slab thickness. The peak acceleration is mainly decreased achieving acceptable vibration behavior by increasing the slab thickness to length ratio for all span lengths studied. The results also indicate that PT floor slabs with practical thickness-span ratios and designed for deflection are expected to be acceptable for vibration. The limits of natural frequency for vibration validity of floors are also discussed.