Abstract: Conducted 4 experiments with 6 albino rat (Rattus norvegicus) colonies. Results show that attack of dominant colony males on introduced strangers produced a nonrandom distribution of bites, with ventral trunk virtually never bitten. Also, vibrissae contact of attacker and defender interfered with bites to the defender's head and upper back. The specific agonistic reactions of attacking and defending Ss appeared to involve strategies based on these limitations on attack: Defenders utilized boxing and lying on the back behavior, which interposed ventral trunk and vibrissae between attacker and defender. In turn, the "lateral display" permitted attackers to circumvent the defender's behavior. Limitations on attack therefore appeared to underlie the specific agonistic behavior of both attacking and defending Ss.