Western experience with solid state fermenters in which the fermenting substrate is circulated is still limited to the laboratory scale (< 20 kg of substrate). In contrast, automated industrial plant with capacities of 10 to 100 t of inoculated substrate per charge have been in operation in Japan for several decades for the semi-continuous production of enzyme mixtures. However, the substrate is only occasionally circulated in these plant. It is shown from the literature cited that stationary solid state fermentation processes employing the tablet method give significantly better results (lower plant costs, shorter process duration, high enzyme product yields, higher product quality, less pronounced gradient formation, etc.) than processes with occasional product circulation. Stationary solid state fermentation plant (tablet method) therefore appear to represent the method of choice, especially for the production of secondary metabolites, pigments, flavours, etc., whose production optima lie within fairly narrow limits which cannot be met by non-stationary units.