This data publication contains information collected as part of a field and laboratory effort to determine prevalence of avian malaria (Plasmodium relictum) and pox-like lesions (Avipoxvirus spp.) in native and non-native forest birds on the northern, high elevation (>1500 m) slopes of Haleakala volcano on Maui during the last decade of the 20th century. Forest bird banding data and blood samples for diagnosis of Plasmodium relictum, the agent responsible for avian malaria in Hawaii, were collected in 1993 and again in 1996 at Hanawi Natural Area Reserve and Waikamoi Preserve. Both areas comprise critical habitat for several species of endangered forest birds including Akohekohe (Palmeria dolei), Kiwikiu (Pseudonestor xanthophrys) and Poouli (Melamprosops phaeosoma) which were still extant in the wild at the time of the study. This data file reports morphometric data, age, sex, molt status, lesion occurrence, and diagnostic results for avian malaria from native and non-native forest birds that were captured with mist nets at the two study sites. This XML describes one tabular CSV file: Maui Banding Diagnostics Data Final.CSV.