Between September 1977 and November 1978, chlamydiosis (psittacoisis) was diagnosed in 52 of 128 parrots, 5 of 12 cockatiels, 2 of 5 cockatoos, 3 of 6 macaws, 1 of 22 conures, 2 of 18 lovebirds, and 6 of 76 parakeets; 2 lories and 1 lorikeet were chlamydiosis negative. Two cases of human chlamydiosis were associated with two submissions of parrots subsequently found to have active infection. Twenty parrots (including 13 that were chlamydiosis positive), 2 cockatiels, 1 macaw, 1 lorie, and 1 parakeet yielded salmonella organisms, of which 16 were identified as Salmonella typhimurium, 8 as untypeable monophasic salmonellae of serogroup B, and 1 as S arizonae. Three S typhimurium from parrots that had been treated with chlortetracycline for chlamydiosis were resistant to tetracyclines, streptomycin, and sulfonamides; another isolate was found to be resistant to chloramphenicol only. Severe giardiasis was diagnosed in parakeets originating from six aviaries.