During some 40 years’ research, ten species of gadfly petrel, Pterodroma spp., have been reported from Holocene fossil assemblages from the Chatham Islands, New Zealand. Statistical analysis of the assemblages’ species composition and a critical appraisal of all claimed identifications have resulted in a re-assessment of fossil Pterodroma diversity prior to human arrival. Three species are confirmed as original breeding residents; the endemic Pterodroma magentae and P. axillaris, and the undescribed extinct Pterodroma sp.1. Additionally, P. nigripennis is confirmed as a vagrant. Possible records of further vagrant species, P. inexpectata, P. macroptera or P. lessonii and P. neglecta cannot yet be confirmed.