Increased frequency of heat waves (HWs) is one of the prominent consequences of climate change. Its impact on human health has been mostly reported in the northern hemisphere but has been poorly studied in the southern hemisphere. The aim of this study was to analyze the effects of the HWs waves occurred in the warm season 2013-14 on mortality in the center-north region of Argentina, where 22 million people live. It was carried out an observational study of ecological-type contrasting the mortality occurred during the HWs of the summer 2013-14 with the mortality in the summers 2010-11 to 2012-13, free from HWs. The mortality was analyzed according to the following variables: place of residence, age, sex and cause of death. During the HWs of the summer 2013-14, 1877 (RR=1.23, 95%CI 1.20-1.28) deaths in excess were registered. Moreover, the death risk significantly increased in 13 of the 18 provinces analyzed. The mortality rates by sex revealed heterogeneous behaviour regarding both the time and spatial scale. The death risk increased with age; it was particularly significant in four provinces for the 60-79 years group and in six provinces in people of 80 years and over. The death causes that showed significantly increments were respiratory, cardiovascular, renal diseases and diabetes.