Cyclohexene epoxides are a small group of naturally occurring oxygenated cyclohexanes, most of which have been found in plants of the Uvaria genus. Some of these molecules possess pharmacological activity and have been isolated from plants that have been used in traditional medicine in Thailand. The biogenesis of these compounds was thought to have been fully explained when all the intermediates of a proposed synthetic pathway had been isolated from a single Uvaria species. Further studies on naturally occurring cyclohexene epoxides identified novel compounds, whose presence could not be explained by the accepted scheme. An alternative biosynthetic pathway that was formerly considered unfavourably appears to fit currently available evidence.