SummaryFive tests based on the use of small leather balls, kept in motion just outside the hive entrance, were used to evaluate the relative aggressiveness of Italian (Apis mellifera ligustica) and Africanized bees (Apis mellifera adansonii) in Brazil. The tests were: period before the first sting; period before becoming fierce; number of stings in the observer's gloves; number of stings in the leather ball; distance that the bees followed the observer. Data obtained from 5 colonies of Italian bees and 9 of Africanized bees showed that the latter were significantly more aggressive.