The present work documents the experimental conditions under which the three types of two local strains of Beauveria bassiana conidia enter into a microcycle conidiation process (conidiation without vegetative phase). Different levels of different C (glucose and starch) and N sources (KNO3, NH4Cl, glutamate and peptone) were added to a basal medium containing buffer phosphate and microelements. No microcycle conidiation was observed in media containing more than 0.00139 g N l(-1) for every N source and all C source concentrations assayed (except when C level was 0 g l(-1)). The absence of the C source, at every level of the N source, produced daughter conidia at the tip of very short germ tubes. The percentage of germinating conidia which underwent microcycle conidiation in 48 h of incubation was not modified by the C source level. Nevertheless, the higher the concentration of the C source added, the longer and the stronger the vacuolated germinating tubes produced. The secondary conidia produced by microcycle conidiation were viable and capable of repeating the cycle for at least two generations. Finally, taking into account the morphological changes during microcycle conidiation three distinct phases which characterized the process were established. The development of reproducible experimental systems where microcycle conidiation can be expressed is important in a complete study of B. bassiana conidiogenesis,