We conducted an empirical study to analyse the association between students" perception of surface and structural analogies among problems, and their algebraic success. Algebraic success was measured by the equations selected to solve each problem. Different surface and structural relationships between one source problem and four target problems were considered. We also considered high (daily life) and low (scientific) familiarity contexts for the problems. Similarities and differences between the source and each target problem were explicitly asked to students. Results showed a significant correlation between detecting the correct structural relation between these problems and selecting the correct equations to solve the target ones. Low familiarity (science) problems obtained lower success independently of other factors. Usual teaching procedures, based on isomorphism, could increase the probability that students consider isomorphism the only possible relationship between problems.