Africanized honey bees, considered a hybrid between African and European bees, are well known for their high defensive behavior. However, previous studies of these bees on the island of Puerto Rico found that they have reduced defensive behavior as determined by two tests of defense, a behavioral assay and a sting assay. Guarding behavior had not been examined. The objective of this study was to evaluate the guarding behavior of Africanized bees in Puerto Rico. Based on previous studies we predicted that there would be no significant difference between guarding of Africanized and European bees on the island. We conducted experiments in three trials. In each trial we cofostered Africanized and European bees in four hives, twoAfricanized and two European. We observed guarding behavior daily for three weeks. According to our observations of the first trial there was no statistical difference in guarding behavior between Africanized and European bees. In the second trial the European bees guarded more often than Africanized bees. In the third trial, which coincided with a nectar flow, there was no significant number of guards in any of the colonies. The seemingly reduced tendency to guard of Africanized bees supports the results of other studies where Africanized bees of Puerto Rico were found to be relatively gentle. These results also support the hypothesis that organisms on islands tend to have reduced defense.