The purpose of multiple choice tests of medical knowledge is to estimate as accurately as possible a candidate's level of knowledge. However, concern is sometimes expressed that multiple choice tests may also discriminate in undesirable and irrelevant ways, such as between minority ethnic groups or by sex of candidates. There is little literature to establish whether multiple choice tests may also discriminate against students with specific learning disabilities (SLDs), in particular those with a diagnosis of dyslexia, and whether the commonly-used accommodations allow such students to perform up to their capability. We looked for evidence to help us determine whether multiple choice tests could be relied upon to test all medical students fairly, regardless of disability. We analyzed the mean scores of over 900 undergraduate medical students on eight multiple-choice progress tests containing 1,000 items using a repeated-measures analysis of variance. We included disability, gender and ethnicity as possible explanatory factors, as well as year group. There was no significant difference between mean scores of students with an SLD who had test accommodations and students with no SLD and no test accommodation. Virtually all students were able to complete the tests within the allowed time. There were no significant differences between the mean scores of known minority ethnic groups or between the genders. We conclude that properly-designed multiple-choice tests of medical knowledge do not systematically discriminate against medical students with specific learning disabilities.