The effect of three configurations of the jaw of kill-traps on time to loss of palpebral reflex of brushtail possums (Trichosurus vulpecula) was assessed. Traps were Standard, with an offset rotating jaw closing past a pear-shaped constriction, Offset, with a rotating jaw closing past a straight edge, and Opposing, with a rotating jaw closing directly onto a static bar. Possums captured in the Standard and Offset traps had significantly lower times to loss of palpebral reflexes (42 and 50 sec respectively) than those captured in Opposing traps (122 sec). Both the Standard and Offset traps achieved total occlusion of both carotid arteries more frequently than the Opposing trap. Thus the killing effectiveness of kill traps designed for capturing possums can be improved by offsetting the jaws without the need to increase the power of the trap. Therefore, for some target species, such modifications might satisfy the demands of animal welfare proponents for traps that kill rapidly, without compromising trapper safety.