Terpenoids are the largest group of natural compounds with a high structural diversity. Synthesized out of five- carbon building blocks they are highly lipophilic, implying a potential effect on the physical and chemical properties of the biological membrane, which are proved to be crucial for each living cell. Terpenoids are synthesised by several enzymes in different organelles within plant cells for instance and the mechanism of transport is so far unknown. We have shown that terpenoids interact with lipid monolayers and we propose that they might have a phase separating effect in lipid membranes, similar to that induced by sterols. Corroborating this hypothesis might open for new explanations for molecular transport in cellular membranes.