High incidences of aspergillosis (12.9%) and candidiasis (15.4%) were encountered in 241 psittacines and passeriformes which died within 2 weeks of quarantine after being imported into Japan. Respiratory aspergillosis was diagnosed in 31 birds which involved mainly the nasal cavity (17 birds), lung (14 birds) and air sac (13 birds). Thirty-seven birds had candidial lesions in various organs, especially in the nasal cavity (22 birds), crop (17 birds), oesophagus (12 birds), proventriculus (6 birds) and gizzard (6 birds). The study provided strong evidence that the nasal cavity was an important entry and multiplication site for the both mycoses in psittacine birds. Aspergillus spp. had an affinity for the respiratory region of the nose, inducing an exudative rhinitis. Two types of tissue reaction, invasive and granulomatous, were found in the lung and air sac, although the former type was predominant. Candida spp. often attacked the vestibular region of the nose. This agent caused a hyperkeratotic change in the nasal cavity and other mucous membranes such as the crop, gizzard and cloaca. Cutaneous aspergillosis and candidiasis with or without poxvirus infection were also observed.