the rice cultivar cica-8 exhibit differential reaction to several pathotypes of magnaporthe oryzae. the objective of the present investigation was to determine the number of alleles involved in the expression of resistance to leaf blast and identify microsatellite markers linked to these alleles. a cross between cultivar metica-1 and cica-8 susceptible and resistant, respectively, to pathotype ib-1 (py1049) was made to obtain f1, f2, bc1:1 and bc1:2 progenies. greenhouse tests for leaf blast reaction showed that resistance is controlled by a monogenic dominant gene. for testing microsatellite markers, dna of both resistant and susceptible parents and f1 and f2 populations was extracted. as expected for single dominant gene the f2 populations segregated at a ratio of 3:1. of the 11 microsatellite markers tested, one marker rm 7102 was found to be closely linked to the resistant allele at a distance of 2.7 cm, in the cultivar cica-8 to pathotype ib-1.