Tesla turbine, a bladeless turbine, was patented by the famous scientist Nikola Tesla (1856–1943) in 1913.1 Up to now, a major stumbling block in its commercial use has been its low efficiency and certain other operational difficulties.2 However, there has been a resurgence of research interest in this type of turbines3 because they have several advantages (as explained below) and hence may be appropriately developed and used in certain niche application areas. In this article, an analytical theory has been developed for predicting the performance of Tesla turbines, which agree well with experimental results