BACKGROUND: scientific literature indicates that there are sex, and gender differences in the development, symptomatology and evolution of different diseases, in the response to drugs and in the therapeutic pathways. Even in the COVID-19 epidemic some sex/gender differences emerged. OBJECTIVES: to analyze COVID-19 epidemic data by gender and age in Italy, Germany, Spain, and Sweden, characterized by having implemented different pandemic containment policies, with the aim of observing any characteristics that can be interpreted with the lens of sex/gender differences. MATERIALS AND METHODS: we used confirmed cases and deaths associated with COVID-19 for Italy, Spain, Germany, and Sweden from respective national surveillance databases. Mortality data for Italy were also analysed. The period of investigation was March-May 2020. As indicators, we used the case fatality ratio adjusted for time delay and SMR for mortality. RESULTS: women are more vulnerable to COVID- 19 infection in the 30-60-year age group. Case fatality ratio is higher in men than women, with a ratio men/women equal to 1.7 in Italy, Spain, and Sweden and 1,4 in Germany. The ratio increases in the lower age groups. The analysis of the mortality data observed/expected in Italy in the same period with respect to 2015-2019 shows a comparable excess with SMR equal to 132 for men and 127 for women. CONCLUSIONS: COVID-19 affects both genders with some differences in the incidence, higher in women, and lethality, higher in men. These differences highlight the need to better understand the sex/gender and age interaction both for epidemiological surveillance and for a better gender-appropriateness of the ongoing prophylactic and therapeutic treatments. This would be possible if all health indicators (symptoms, past illnesses, primary and hospital-level health care, hospitalization, etc.) were provided by age and gender. Analysis of the causes of death could help to better understand the increase in mortality for both genders, in particular for women, for whom a lower lethality for COVID-19 appears from data.