The aggressive behaviour of Anochetus ghilianii (Spinola, 1851) was estimated in the laboratory by observing the outcome of individual confrontations between workers belonging to 17 colonies according to the geographical distance between these colonies. This study aimed to better understand the social organization of this species and its mode of reproduction and colony foundation. Three categories of behaviours were exhibited by the opponent ants: aggressive, low-aggressive and non-aggressive. The latter category was the most prevalent with an average percentage of 82.56%, and prevailed in eight colonies. Conversely, aggressive behaviours represented only 9.61% of the records on average and appeared only when distance between colonies exceeded 1500 m. In addition, the percentage of aggressive behaviours considerably increased in relation to the geographical distance between the colonies. There was a significant positive correlation for aggressive behaviours, and negative for non-aggressive behaviours. This low level of aggressive behaviour suggests a short genetic distance between colonies which could have arisen through colony fission reproduction (dependent colony foundation).