Trade Unions, resulted from revolutionary changes in social and working conditions caused by the industrial revolution, since the day they appeared, have developed in a male-dominant structure and in these structure problems of unionized women workers have always remained in the background. In the study, the problems of unionized women that they encounter in unions were studied by employing interview method as a qualitative research method. The obtained results were investigated by content analysis and various reasons for the problems were reached. These reasons include lack of attendance to union organizations owing to their role in the family, the fact that their responsibilities prevent them from participating in management and institutional/employer strictions regarding this participation, the fact that unions inadequately deal with sex-based problems of theirfemale members and that there’s a hidden gender apartheid in codetermination. By individual interviews and literature reviews, it was concluded in the study that unions may overcome these problems by addressing their female members’ problems and by enabling more women to take active roles in unions’ decision making bodies