As in other developing countries, Colombia has underwent an intense process of market oriented reforms at the beginning of the 1990s. This study analyses the extent to which income distribution and poverty changes in Colombian urban areas between 1990 and 2004 may be explained by gender dynamics in the labour market. For this purpose, the authors use household surveys microdata in order to perform a microsimulations analysis, following the methodology proposed by de Reis and Paes de Barros (1991). As a main conclusion, it is found that if labour market conditions of 1990 had prevailed in 2004, there would be a deterioration of poverty, income distribution and gender labour income inequality. In addition, it is observed that poverty headcount ratio diminished between 1990 and 2004 in urban Colombia but the number of men and women living with incomes below the poverty line grew up during this period.