Different factors likely tu improve and induttion in Phaseolus vulgaris L. and P. coccineus L. were tested. Tite highest frequencies of callos induction were obtained for the P. vulgarls genutypes, \tlth Murashige & Skoog based-medium, suppicmen!ed with kinetin (2 mg/1), 2,4-D (2 mg/1), the vitamins of B5 medium, casein hydrolysate. agarose and a carbon source (l2.5 to 2S g/l of either sucrose or maltose), in the following conditions: 40 antbers in Petri disbes wtth a diameter Qf 55 mm containing 1O ml of medium, in the dark and at 26°C, with a cold pretreatment of the flower buds of l or 2 days. The analysis of the Calli by microfluorometry revealed a high frequency of haploid cells.