A surgical access assembly for receiving instruments of various diameters is disclosed. The access assembly includes a housing defining a longitudinal axis and having a longitudinal opening for passage of a surgical instrument. The access assembly may also include a mechanism disposed within the housing and having a passageway for reception and passage of the surgical instrument in substantial sealed relation therewith. The mechanism may be adapted for reciprocal longitudinal movement within the housing between a first position corresponding to a first dimension of the passageway and a second position corresponding to a second dimension of the passageway. The mechanism may include a single seal element or first and second seal elements. The seal elements may be adapted for lateral movement during longitudinal movement of the seal. The first and second seal elements may be in at least partial overlapping relation when in the first position of the seal. The access assembly may include a lock or latch for preventing movement of the seal elements.