The aim of this paper was to assess the impact of heat-waves on mortality in ten Czech cities, using data recorded during the summers of 2015 and 2016. Temperature-related mortality during heat-waves was investigated by comparing mortality figures on heat-wave days and those on other days by means of the Mann-Whitney U test. Results for all-cause mortality, cardiovascular and respiratory diseases (CVD+R) mortality, as well as for mortality in the over-65 age group, show statistically significant differences (p <0.05) during heat-waves compared with other days in seven of ten cities investigated. The effect of heat-waves on mortality did not reach statistical significance in Olomouc, Plzeň and Liberec. The results suggest that further studies addressing spatial patterns of mortality during heat-waves in urban areas are required to assess the vulnerability of the urban populations in particular cities and types of neighbourhood.