The 25th Aviation Battalion arrived in Vietnam on 30 April 1966. Company A transferred to Vietnam less personnel and equipment. Upon arrival Company A was organized, manned and equipped with UH-1 helicopters using the assets of the 175th Aviation Company arriving from Fort Benning. The 175th was then inactivated on 5 May 66. The 25th Aviation Battalion was based at Cu Chi Vietnam.
Company A (Little Bears) served as an assault helicopter company and Company B (Diamond Head) served as an attack/support helicopter company. The battalion participated in twelve Vietnam campaigns receiving two Valorous Unit Awards and two Meritorious Unit Commendations. In addition Company B received a Presidential Unit Citation.
In 1969 the battalion received the Outstanding Aviation Unit Award. The award, established by the Army Aviation Association of America, is given on an annual basis to recognize the best aviation unit in the active Army. The 25th Aviation Battalion received the award for the period 31 March 68-31 March 69 primarily in recognition of a 70 percent increase in flying hours with a 28 percent reduction in accidents in support of the combat operations of the 25th Division.