Cotton is a mycotrophic plant in which growth and nutrient uptake is usually, increased by mycorrhizal colonisation (Nehl et al. 1998). The 'Northern, Development of the Cotton Industry' is based upon a sustainable cotton, farming system. Elements include: No-till / minimum and reduced tillage, use, of mulch cover to reduce soil erosion, appropriate crop rotations, and, integrated pest management systems (O'Gara 1998)., Very little information is available about the mycorrhizae associated with crop, plants in the NT. A preliminary investigation in 1987 of maize plants and their, mycorrhizae found infection levels up to 45% (J.P. Thompson, Leslie research, Center, QDPI, Toowoomba). No information is available on commercial, cotton and its companion crops. This project aimed to provide information on, the density and diversity of mycorrhizal fungi associated with cotton and trap, crops grown at the Katherine Research Station (KRS). Additionally, samples, were taken from native collateral relatives of commercial cotton: Hibiscus, meraukensis and H. leptocladus