A total of 1531 diagnostic submissions from birds were examined by culture for the presence of Chlamydia psittaci between June 1976 and December 1984 by growth in NCTC 929 clone L mouse fibroblast cells, pretreated with an inhibitor of cell division, followed by direct immunofluorescence microscopy. Of these, 196 were found positive. The continued importance of psittacine birds as potential sources of infection was shown by the high number of positives (139) obtained from birds of that order. The percentage of submissions found positive was highest in parakeets (30·1) and was fairly high in psittacines as a group (16·6), but the latter figure was exceeded by the group ofcollared doves (Streptopelia decaocto) and wood pigeons (Columba palumbus) (25·0). Domestic poultry generally gave low rates, turkeys being the highest.
Both the numbers of submissions and their rates of positives increased between 1980 and 1984.
Comparing the isolation rates from the various organs sampled, the intestines gave the highest rate (20·4 per cent positive), closely followed by the other internal sites. The superficial swabbed sites (eye, nasal cavity, cloaca) gave lower rates.