The research focused on analysing of the content of gender mainstreaming in the collective agreements at company and sector levels, in the activities (especially collective bargaining) of the social partners - particularly the trade unions - in the surveyed companies or sectors. The contents of the relevant collective agreements (company and sector collective agreements) were analysed, and the semi-standardized interviews were conducted with the respective collective bargainers in the Slovak Republic (SR). The research shows that social partners in SR, especially unions, rank themselves among the leading partners in the processes, and are aware of their specific role and function in those processes. They have been acting in area of the principles and practices concerning reconciliation between work and private (family) life for a long time and at a standard European level. They included the agenda of equal opportunities in their objectives and principles. Now they are learning how to effectively include the agenda in their day-to-day activities, especially the life of their company's employees. The surveyed Slovak collective agreements are, in principle gender neutral (in the formulations as well as in the content). They generally go beyond the framework of the law in providing more rights and advantages for the employees. In general, the surveyed collective agreements established more specific instruments and measures for reconciliation between work and family (private) life than for implementation of equal opportunities for men and women. Instruments and measures aimed at reconciliation between work and family are connected especially with the use of the social fund of the enterprise and guarantee to the employees more paid free days (for e.g. caring for sick family member, wedding or funeral in the family, accompanying child to school on child's first school day) than provided under the Labour Code, application of the flexible working time and organising of the various cultural, sport, leisure and recreational activities for families of the employees.