Aims: To purify and characterize the chitinolytic activity of Penicillium janthinellum P9 and to evaluate possible uses of the purified enzymes in the control of fungal growth and spore germination. Methods and Results: The chitinolytic activity of P. janthinellum P9 was associated to two beta -N-acetyl-hexosaminidases (CHI1 and CHI2) that were purified by preparative isoelectric focusing and preparative electrophoresis and partially characterized. Treatment of test fungi with purified enzyme solutions caused reduced spore germination, reduction of hyphal length and mycelial damage. The combined action of the two enzymes and a systemic fungicide completely inactivated pests and food-spoiling moulds such as Fusarium solanii, P. canescens and Cladosporium cladosporioides. Treatment with the two enzymes increased germination of freeze-dried fungal spores. Conclusions: The chitinolytic activity of P. janthinellum P9 is associated with two extracellular beta -N-acetyl-hexosaminidases that can cause damage to the cell walls of other fungi. Significance and Impact of the Study: This appears to be the first report on the characterization of extracellular chitinolytic enzymes produced by a Penicillium strain. The results of this study might have some impact in the applied research field.