Infection by Chlamydophila psittaci (formerly Chlamydia psittaci) is a common cause of morbidity and mortality in companion psittacine birds and is transmissible to humans. Replication of Chlamydophila is inhibited by plasma doxycycline concentrations greater than 1 μg/ml, but prolonged treatment periods of 30–45 days are needed to eliminate infection. Medication of birds for this prolonged period is difficult with current treatment methods. In this study, drinking water medicated with doxycycline hyclate at 800 mg/L was provided ad libitum to healthy African grey parrots (Psittacus erithacus timneh) and Goffin's cockatoos (Cacatua goffini) for 42 days. Blood samples for doxycycline analysis were collected on treatment days 4, 7, 14, 21, 28, 35, and 42. Mean doxycycline concentrations exceeded 1 μg/ml throughout the 42-day treatment period. In the African grey parrots, the mean doxycycline concentration (± SD) for all plasma samples collected during the study was 1.51 ± 0.68 μg/ml and doxycycline concentrations were greater than 1 μg/ml in 73% of the samples. In the Goffin's cockatoos, the overall mean was 2.78 ± 1.00 μg/ml and doxycycline concentrations exceeded 1 μg/ml in all samples. No adverse effects were noted in the African grey parrots. All of the 8 treated Goffin's cockatoos were physically healthy, but changes in plasma biochemical analyses suggested mild hepatic damage in 3 birds. Results of plasma biochemical analyses in these cockatoos were within reference ranges when retested 7 days after doxycycline treatment ended. The results of this study suggest that doxycycline-medicated water can safely maintain plasma concentrations adequate for treating avian Chlamydophila infections in African grey parrots and Goffin's cockatoos housed under standardized conditions.