Cannabidiol (CBD) is a natural alkaloid present in Cannabis sativa. It is used in the treatment of specific types of epilepsy and a wide range of other possible indications are currently under investigation. CBD is a highly lipophilic drug (logP 6.3). It has been previously shown that drugs with logP > 5 have a potential of significant lymphatic transport through mesenteric lymph vessels on oral administration. This type of absorption could be of great pharmacological importance because it reduces the liver first-pass elimination and brings the active substance into the intestinal lymphatic system, where the CBD immunomodulation effect can come into play. We used our anaesthetised lymph duct cannulated rat model and quantified the extent of CBD lymphatic transport. Additionally, standard pharmacokinetic studies comparing oral bioavailability of two CBD formulations (microemulsion and sunflower oil solution) were conducted. In the results, CBD oral bioavailability was 25% for microemulsion and 14% for sunflower oil solution. CBD lymph concentrations were two to three orders of magnitude higher than serum concentrations. Exactly quantified, 39% and 55% of systemically available active substance has been found in the mesenteric lymph after microemulsion and sunflower oil solution administration, respectively. In conclusion, CBD shows moderate to low bioavailability after oral administration. On the other hand, lymphatic transport plays a crucial role in the process of intestinal absorption and distribution. [ABSTRACT FROM AUTHOR]