Clinicians often use foot orthoses to manage the symptoms of plantar fasciitis. Although there has been considerable research evaluating the effectiveness of orthoses for this condition, there is still a lack of scientific evidence that is of suitable quality to fully inform clinical practice. Randomized controlled trials are recognized as the "gold standard" when evaluating the effectiveness of treatments. We discuss why randomized controlled trials are so important, the features of a well-conducted randomized controlled trial, and some of the problems that arise when trial design is not sound. We then evaluate the available evidence for the use of foot orthoses, with particular focus on published randomized controlled trials. From the evidence to date, it seems that foot orthoses do have a role in the management of plantar fasciitis and that prefabricated orthoses are a worthwhile initial management strategy. At this time, however, it is not possible to recommend either prefabricated or customized orthoses as being better, and it cannot be inferred that customized orthoses are more effective over time and therefore have a cost advantage. Additional good-quality randomized controlled trials are needed to answer these questions.