In laboratory tests, groups of about 500 termites (Reticulitermes flavipes) were offered a choice between untreated blocks of slash pine, and blocks of sweetgum, made attractive by partial decay with Gloeophyllum trabeum and impregnated with antibiotics. Data are tabulated showing that numbers of (symbiotic) protozoa were not reduced by impregnation with atabrine and chloroquine, possibly because termites did not feed readily on such wood; these antibiotics may, therefore, have some potential in termite control. Impregnation with chlortetracycline reduced numbers of protozoa per termite and caused weight loss and reduced survival; recommendations are made for its use in the bait-block method of control. -- AATA