In March 2003 the Texas State Guard Medical Reserve Corps (MRC) was officially formed as a component of the Texas Military Forces, under the Texas Adjutant General, and at the express direction of the Governor of Texas. Initially, the Medical Reserve Corps was cosponsored by, and to this day still has a working relationship with, The University of Texas Health Science Center at San Antonio and other state-supported health science centers. Reorganized as the TXSG Medical Brigade (MRC) in May 2007, the membership has increased to over 400 statewide.

The Medical Brigade was created as a regional medical response team that can be called upon to assist in Texas public health emergencies, including biological terrorism, epidemics, and disasters. The primary mission of the Texas State Guard Medical Brigade is to augment the emergency response efforts of local public health authorities that require additional assistance. Additionally, upon approval of the Medical Brigade command, units participate in local community events to augment on-site healthcare providers, usually in support of TXSG safety/security teams deployed to assist with safety-related activities.

The ranks of the Medical Brigade are composed of trained, licensed and certified health care professionals and medical support personnel who constantly train and prepare to support state and local public health authorities with surge capability and specialized emergency skills. These individuals serve in various roles depending on the nature of the emergency for which they are called to assist. Units can provide mission-specific response teams or individual cadre depending on the scope and size of the mission. The intent and purpose of the Medical Brigade can best be described as "Texans helping Texans."

The Medical Brigade expects to grow to over 1000 personnel statewide. Medical Brigade Groups are presently located in Dallas / Fort Worth, Houston, Laredo, Midland-Odessa, San Antonio, Temple, and Tyler. Medical Brigade Companies are located in Austin, Corpus Christi, El Paso, Fredericksburg, Galveston, Lubbock, Rio Grande Valley, and Wichita Falls, with plans underway for the formation of companies in other cities throughout the state. The TXSG Medical Brigade may establish a detachment or company in cities or areas where 20 or more enlist and an element commander is selected and commissioned.