An experiment was devised to test the empathising-systemising (E-S) theory of autism. Three groups of participants took part in the study: males with Asperger Syndrome (AS) (n = 18), males without AS, (n = 44) and females from the general population (n = 45). Each participant completed two tasks: one that involved empathising and another that involved systemising. On the empathising task, females scored significantly higher than control males who in turn scored higher than males with AS. Conversely, females scored significantly lower than both male groups on the systemising task, who did not differ significantly from each other. These results are in line with both the E-S theory of autism and the 'extreme male brain' theory of autism. Alternative explanations of the results are also explored, including an interpretation through the idea of open and closed systems.