The article develops a comparative study between Chile and UK regarding the functioning of its system of post legislative scrutiny. To assess this issue, the different types of legislative scrutiny are briefly introduced to then focus on the scrutiny carried by Parliaments after the legislation is enacted. The comparison between both countries is made according to the compliance with the standards of: (i) effectiveness, (ii) efficacy and (iii) efficiency. The article examines how the Chilean and UK system of post legislative scrutiny achieve each of these goals, concluding that the UK model is overall a more successful system of post legislative scrutiny. Nevertheless, some recommendations are put forward to further improve the system of post legislative scrutiny in both countries.