This study included 234 Nurses employed at chemotherapy units: 165 from Poland; 69 from Slovakia. The participants were examined with previously validated versions of Meister Questionnaire. In the assessed dimensions of mental load, Monotony and Unspecific Load (reaction to stress) differentiate the Nurses working at chemotherapy units in Slovakia and Poland. The working conditions of Nurses providing care to oncologic patients treated with chemotherapy both in Slovakia and Poland are connected with a burden which is the result of time pressure and excessive responsibility. Assessment of the mental load can be used to improve the organization of Nurses’ work creating safe working conditions in both studied countries, taking into consideration the mobility of the workforce in the European Union.