A photo-identification study of bottlenose dolphins (Tursiops truncatus) was performed in the northern Gulf of San Matías, Patagonia Argentina, during the period 2006-2008. In total, 199 surveys were conducted with an average observation effort of 4.2h (SD=1.5) per survey. These surveys resulted in a total observation effort of 824.7h of which 105.7h was spend with 158 dolphin groups. Over 12,500 pictures were analysed using the automatic identification systems FinEx and FinMatch (EuroPhlukes Initiative, Leiden University, The Netherlands), resulting in the first identification catalogue of 47 dolphins for the North Patagonian region. The catalogued dolphins were re-identified up to 13 days with 57% (n=47) showing a degree of residency for the Natural Protected Area Bahía de San Antonio (NPABSA; resighting frequency (RF)≥4). At least 6 dolphins, including one mother with her calf, were additionally re-identified inside the estuary of the river ‘Rio Negro’, 250km east, indicating that their home-range includes at least the whole northern region of the Gulf of San Matias. Data suggest that it concerns a stable but yet unknown population of bottlenose dolphins with a high touristic potential and an urgent need of conservation measurements. The obtained photo-identification catalogue is meant to serve as a tool for the conservation of the species and the realization environmental education projects in the region.