The distribution of microorganisms in stabilised and unstabilised sand dunes has been studied at three sites in the Indian desert. The population of fungi, bacteria, actinomycetes, Azotobacter and nitrifying bacteria (Nitrosomonas spp.) was low, as in other deserts, but the percentage of actinomycetes was higher than that of fungi. Stabilisation of dunes led to approximately a 200-fold increase in the microbiological population. The population of actinomycetes decreased with depth after 30 cm, while bacteria and fungi generally declined with increasing depth from the soil surface. Azotobacter and nitrifying bacteria in stabilised dunes were higher than in unstabilised dunes.