Nestmate recognition systems in ants are a controversial subject. Twomain chemical recognition systems have been proposed. One suggested thatthe secretions from the mandibular glands are responsible for nestmaterecognition in ants of the genus Atta. The other suggested thatthe postpharyngeal gland provides the “Gestalt” odour responsible for nestmaterecognition in the ant Cataglyphis niger. We explored the functionof the postpharyngeal gland as a putative source for nestmate recognitionin the ant Atta laevigata with field tests. Through recognitionbioassays, we confirmed that A. laevigata can discriminate betweennestmates and non-nestmates, and the odours responsible for nestmate recognitionare concentrated in the head. Non-nestmate ants are more frequently bittenthan nestmates. However, in several experiments where nestmates and non-nestmateswere odourized by brushing postpharyngeal glands of nestmates and non-nestmatesthroughout the thorax, no clear evidence of recognition were found. Additionally,the chemical composition of the postpharyngeal gland was characterised,and mainly n-long chain and branched hydrocarbons were identified. Theresults suggest that A. laevigata has a different chemical recognitionsystem compared to Cataglyphis niger.