Cultures of BHK monolayer and suspension cells obtained from a number of laboratories and a group of cloned sub-lines derived from suspension cells were examined for their susceptibility to three FMD virus strains. It was found that the various cultures were sensitive to the test virus strains to differing degrees. It was shown possible to obtain a clone with high susceptibility to Asia 1 Iran 1/73 virus from a parent culture which had a low susceptibility to that virus. The implication of these findings is discussed.