In this paper, we propose a novel efficient frame slotted aloha (EFSA) protocol for radio frequency identification (RFID) tag anticollision in this paper. After successfully identifying each tag, the EFSA protocol will allocate the tag a slot number, which signifies when the tag could be identified during a read cycle. When no tags arrive and leave, idle slots and collision slots will not be produced in subsequent read cycles. In addition, if there is a collision slot in the EFSA protocol, colliding tags in the collision slot will be resolved by Q -ary splitting where Q is equal to the estimated number of colliding tags, while the other unidentified tags is in a waiting state until the colliding tags are successfully resolved. Since allocation of tags to slots is not random in the EFSA protocol, conventional tag quantity estimates are not suitable. Therefore, we also propose a novel tag quantity estimate for the EFSA protocol. Simulation results show that the EFSA protocol outperforms conventional protocols, in term of time slots of reidentifying tags, and the proposed estimate error is less than the conventional estimates in the EFSA protocol.