Root nodules collected from the non-leguminous plant Trema cannabina Lour. grown under natural field conditions were examined for the presence of leghaemoglobin. No trace of any soluble haemoglobin-like compound could be detected by spectrophotometric analysis or molecular weight comparison studies, although a small amount of soluble haemoprotein with peroxidase activity was isolated. Possible alternatives to the possession of a leghaemoglobin in non-legume/Rhizobium N2-fixing associations are discussed.