Production of proteinases with plasmin-like and plasminogen-activating activities by a micromycete Arthrobotrys longa 1 was studied. Polycyclic growth of the producer in submerged cultures was observed, with an endogenous rhythm of the periods of intense microconidia formation alternating with the phases of drastic increase in the content of producing mycelium. The highest plasminogen-like and plasminogen-activating activities (up to 1000 and 500 cond. U/mL, respectively) were found to correlate with the polycyclic growth of the producer, coinciding with the stage of microconidia germination. Enhanced secretion of proteinases with plasminogen-like and plasminogen-activating activity was found to be associated with increased specific growth rate of A. longa l.