Two hundred tomato germplasm lines were screened following conventional (sick plot and artificial inoculations in pots) and molecular marker techniques to identify resistant sources. PNR-7 and Punjab Upma were used as resistant and susceptible checks, respectively. Seven lines viz . Hisar Lal, EC631955, EC631956, EC631957, EC119197, 8-2-1-2-5 and 1-6-1-4 were found to possess high degree of resistance and two lines viz . EC 531804 and PAU Acc.-1 were found resistant through conventional screening. The resistant lines along with some hybrid combinations involving resistant x susceptible parents were then screened using SCAR marker Mi23 , linked to the RKN resistant gene Mi-1 . The lines Hisar Lal, EC631955, EC631956, EC631957, EC119197, EC531804, PAU Acc-1, 8-2-1-2-5 and 1-6-1-4 amplified... the expected product size of ∼380bp linked to the Mi locus conferring resistance to RKN. Punjab Upma, the susceptible check along with two susceptible test lines generated the ∼420bp band showing absence of Mi locus. The hybrids 8-2-1-2-5 x Punjab Upma, Hisar Lal x Punjab Upma, EC119197x Punjab Upma and Hisar Lal x CR2P-8-6 generated both the bands and were, therefore, heterozygous for the resistant locus ( Mi-1/mi-1 ).