Growth studies of Catenaria anguillulae isolates in response to sodium chloride indicated that all the isolates grew in linseed oil-cake agar medium containing sodium chloride up to 1.0%. Medium with 1.5% sodium chloride, however, completely checked the growth of all the isolates. The size of zoosporangia greatly increased with abundant zoospore production in medium containing sodium chloride at 0.5%.