This paper examines differences between women’s and men’s wages in 18 selected OECD countries in the period 1970 to 2005. The study is based on 12 manufacturing sector- and skill-specific sets of panel data on the gender wage gap. We apply a system generalised method of moments (GMM) estimator to the extended version of the conditional gender wage gap convergence equation, controlling for sector concentration and industry-specific measures of openness using a difference-in-difference approach: trade-affected concentrated sectors versus trade-affected competitive sectors. The results indicate that: (i) an increase in sector concentration is associated with wage gap growth; (ii) both import and export penetration are associated with a reduction of the high-skill gender wage gap growth in concentrated industries; (iii) there is evidence of a widening impact of trade on the medium and low-skill occupational gender wage gap growth in less competitive industries; (iv) institutional regulations of the labour market have an impact on the development of the gender wage gap: for highly-skilled labour an increase in labour market regulation raises the growth of the gender wage gap, while for medium- and low-skilled workers, it lowers it.