In this paper we report the apparently seasonal presence of fin whales in Mejillones Bay (23°S), in northern Chile.We compiled a total of 19 sightings representing 95 whales, including 2 mother-calf pairs, between July and October 2006-2014.We observed groups of 1-10 individuals (mean 5 ± 2.7 ind.) principally in nearshore waters, 30-1000 m off the southwestern tip of Mejillones Bay in austral winter/spring.Fin whales came close to, and potentially overlapped with, the main port access routes of large cargo vessels.Information from real-time monitoring of whale presence relayed to Port Authorities is suggested as to avoid collisions.