Trade Unions in Companies: How are Male and Female Wages Affected? Union action can influence wages at two levels: at centralised industry level and at decentralised corporate level. This study looks at the effects of union action at decentralised level and compares, in particular, its effects on male and female wages. There are a number of sides to the question. First of all, we compare how frequently men and women benefit from the presence of a union representative. Frequency is found to be lower for women due to the types of jobs they hold, which have a slightly negative effect on their wage level. When unions are present, the second question is whether they have parallel effects on male and female wages or whether the union has a tendency to bridge the gap. The findings are two-sided. On average, women's wages benefit more than men's from having a union representative in their firm. Yet this is due to a structural effect. For example, men are more frequently executives and executives' wages are not very sensitive to union presence in firms. So it is not surprising to find that, on average, women benefit more from union presence. This advantage disappears in a comparison of men and women with the same characteristics, which finds that union presence has more of a neutral effect on the wage gap between men and women.