Dallas County Health Department was organized in 1919. It was composed of a full time county physician and a sanitary inspector. In 1933, the first paid nurse joined the staff. The population served in 1939 was estimated at 60,900. Total budget for the year was $29,696.80.

In 1956, there were eight deaths due to rabies in the USA, four of them occurring in Dallas, which was termed the "Rabies Capital of the World". A rabies control program was initiated that year and has been very successful. There have been intermittent discussions of a possible merger between the Health Departments of Dallas County and the City of Dallas. In 1947, the Dallas County Medical Society urged that a combined City-County Health department be established. This call was reiterated in 1952 and resulted in the design and construction of the Dallas City-County Public Health Center in the late 1950's. In 1975, the Community Council of Greater Dallas reported on the organization of a countywide public health service.

In 1976, a search for a qualified physician to fill the combined position of Dallas County Health Office/Director, Dallas County Public Health Services was begun. This physician was charged with the responsibility of forming a single department to serve all the municipalities in Dallas County. Plans were developed for the transfer of certain programs from the City to the County as the first step in the eventual transfer of all public health activities to management by the County. Three programs: Tuberculosis Control, Sexually Transmitted Disease Clinical Services and Epidemiology /Communicable Disease Control and it's supporting Laboratory were transferred in 1980.

The Dallas County Health Department and Dallas County Human Services were merged in 1996 to create the current Dallas County Department of Health and Human Services.