After extensive conversion beginning in early-mid 1966, which included a helicopter landing pad, she was commissioned 28 January 1967 at the Philadelphia Navy Yard.

Colleton arrived in Vung Tau, Vietnam on 2 May 1967 for duties in the Mekong Delta under Commander River Assault Flotilla One (also known as Task Force 117 (TF117)).

It was determined that the MRF needed a larger medical treatment and patient holding capacity and as a result, Colleton was refitted at U.S.

Arriving in South Vietnam just days before the Tet Offensive, Colleton handled 890 combat casualties from 29 January 1968 – May 1968, admitted 134 patients to the ship's ward, and evacuated 411 after providing emergency life-saving treatment and stabilization.

Colleton was decommissioned December 1969 in Bremerton, Washington, stricken from the Naval Vessel Register 1 June 1973, and sold to American Ship Dismantlers, of Portland, Oregon for $172,226.62 on 1 August 1974.