The effect of initial glucose concentration (30-450 g/litre) on the growth of Aspergillus niger 10 in submerged (SMF), agar surface (ASF) and solid state (SSF) fermentations was examined. Biomass production and specific growth rate were considerably less sensitive to changes in initial glucose concentration in SSF compared to either ASF or SMF. In all cases, maximum specific growth rates (0.323, 0.247 and 0.134 1/h for SSF, ASF and SMF, respectively) were obtained with the lowest initial glucose concentration employed (50 g/litre for SSF and 30 g/litre for both ASF and SMF). The rates of glucose uptake in SSF were considerably less affected by initial glucose concentrations when compared with ASF and SMF. Complete consumption of glucose in SSF, ASF and SMF was observed when glucose was applied at initial concentrations of 200, 150 and 100 g/litre, respectively. These results indicate that SSF is more suitable than either ASF or SMF for the growth of filamentous fungi, especially under conditions where catabolite repression applies (e.g. due to high glucose concentrations).