Silkworm larvae infected transovarially with Nosema bombycis were fed with an aqueous suspension of Bavistin (50% carbendazim w/w) at 2 and 3% concentrations. The treatments increased the survival of worms and reduced the pebrine infection in the lot significantly, although complete elimination of infection was not observed. Significant beneficial effects of the treatments at 2 and 3% were also observed with respect to larval, cocoon and cocoon shell weights and cocoon to shell ratio. However, treatments with Bavistin at 4% concentration produced an adverse effect on cocoon characters.