For rapid improvement of the productivity of producer strains, it has been assumed that development of miniaturized cultivation method is crucial for a large screening of high-yielding mutants. From our previous experiments, we found that maximizing the biosynthetic capability of lovastatin-producing fungal cells was very difficult in a miniaturized tube culture (i.e. 10ml tube-culture with 5 ml working volume), because gas-liquid oxygen mass transfer rates always became significantly diminished due to the filamentous morphology of the producing mycelium. In this paper, we are going to report a cultivation method that could facilitate oxygen transfer into the fermentation broth to a great extent, even in the miniaturized tube-cultures. It was observed that, for maximum production of lovastatin, the producers should be proliferated in condensed filamentous forms in miniaturized growth cultures, so that optimum amounts of highly active cells could be transferred to the production culture-tube as reproducible inoculums. Under this highly controlled fermentation conditions, compact-pelleted morphology of optimum size (less than 1mm in diameter) was successfully induced in the miniaturized 10ml tube of the production culture, which turned out to be prerequisite for the maximal utilization of the producers' physiology leading to significantly enhanced production of lovastatin.