This paper focuses on the health reforms during the republican Spain (1931-1939) and the crisis derived from the three-year of civil war. It considers how the war affected the health system and the impairment of health conditions of the population during the late 1930s, considering the changing conditions caused by the conflict. Some of the specific topics analysed are the changing healthcare system, the adaptation of health organization after the outbreak of the war, the impact of the war on the health of the population and epidemiological changes, the problem of the refugees and the clinical studies by experts, mainly on undernourishment.