3D television (TV) and cinema have experienced a recent surge in popularity aided in part by the success of films such as "Toy Story 3" and "Avatar". In parallel with this trend there have been increasing concerns about the safety of 3D TV and cinema for patients with photosensitive epilepsy. General practitioners, paediatricians and neurologists are being consulted about their opinions on the risk of triggering a seizure. Photosensitive epilepsy occurs in 1 in 4000 of the population but the incidence is higher in people aged 7-19 years. We found little evidence in the literature and confusing advice on various websites. We discuss this evidence in an attempt to clarify the advice that health professionals should be giving on this issue. We conclude that 3D cinema and television are only unlikely to trigger seizures in patients with non-photosensitive epilepsy. In young people with photosensitive epilepsy the risk of triggering a seizure is not greater with 3D TV or cinema than with conventional television, and we suggest means by which this risk can be minimised. We suggest removing 3D glasses when watching conventional TV to prevent the eyes from picking up flicker. Unfortunately there is currently insufficient evidence to draw more formal conclusions and clinical trials would be of great benefit.