We observed a Giant Trevally (Caranx ignobilis) ramming and mortally injuring a pair of adult Blacktip Reef Sharks (Carcharhinus melanopterus) in the Palau Islands of Micronesia. Such ramming behavior is known to Palauan and Marshallese fishermen for large-sized individuals of several different species of jacks (Carangidae). In addition, we interviewed knowledgeable Palauan subsistence fishermen regarding episodes of ramming that they had witnessed. Our observations suggest that ramming of sharks may be a normal aspect of jack aggressive behavior. These observations expand our knowledge of social behavior between sharks and large jacks.