Rice, despite being relatively insensitive to boron (B) deficiency (Rerkasem et al 1988, Rerkasem and Jamod 1997), suffers from this disorder in Pakistan (Chaudhary et al 1977) and elsewhere (Shorrocks 1997). For example, about 0.6 million ha of rice in Pakistan suffer from B deficiency (NFDC 1998). Although B fertilization is the simplest and most cost-effective solution to the problem, various practical constraints prohibit its adoption by farmers cultivating low-B soils. Genetic variation in B acquisition and efficiency in biomass production is manipulated in many crop species for managing B deficiency (Rerkasem and Jamod 1997). Therefore, we studied some major rice cultivars in Pakistan for their comparative B efficiency.