Background: This paper presents the results of the study concerning mutual relations between work–family conflict and family– work conflict in the context of age and sex. Material and Methods: The study included 223 subjects (115 women, 108 men, 74 mothers and 61 fathers), aged 21–63. The Work–Family and Family–Work Conflicts Questionnaire and socio-demographic questionnaire were used as the survey tools. To verify hypotheses the correlation analysis and the Mann-Whitney U-test were used. Results: It has been found that a stronger work–family conflict is experienced by the examined men and fathers and a stronger family–work conflict is observed among parents. The results of the statistical analysis showed that there is a significant relationship between the number of working hours per day and work–family conflict and family–work conflict. Work–family conflict among mothers is significantly correlated with the income. The family–work conflict is stronger in the middle adulthood group. Conclusions: There is a significant relationship between sex and age and work–family conflict and family–work conflict. Med Pr 2014;65(4):521–533