The imminent introduction of transgenic crops into Kenya requires a rigorous assessment of the potential risks involved. This study focused on the possible effect of Bacillus thuringiensis ä-endotoxin [CryIA(c)] on arbuscular mycorrhizal fungi (AMF) associated with sorghum. In green house experiments, sorghum seedlings were inoculated with a mixed culture of AM fungi and grown in black cotton soil that contained increasing concentrations of B. thuringiensis toxin. The plants were sampled after 2, 4, 6 and 12 - week intervals. There was a progressive increase in AMF colonization from the 1st harvest (after 2 weeks) to the 4th harvest (after 12 weeks) in all treatments. Additionally, the total root length, fresh shoot weight and fresh root weight was not influenced significantly by the presence of the Bt toxin. These findings suggest that the presence of the Bt toxin in soil does not affect AM of sorghum.