The robustness of complex networks, like metro networks, is a really important issue to our daily life. With robustness we indicate the extent to which a network can deal with challenges imposed on the network, such as failures or attacks of nodes and/or links of the network. In this case the stations of the metro networks are the nodes of the complex network and the rail tracks are the links. The robustness of these networks will be related to the expected relative size of the largest connected component as a function of node failure probability of the network for the specific case of random nodes removal, which is presented in plots. The plots show that the smaller metro networks are more robust than the larger ones, at least according to our definition of robustness. The smallest network is the network of Rome with 5 nodes and the largest one is London with 83 nodes. Also the numbers of iterations which are needed to calculate the largest connected component and the impact of two networks, with same number of nodes and various numbers of links, on the expected relative size have been discussed in this report.