Incubation of Mycobacterium tuberculosis and M smegmatis cells with the sugar components of their surface-exposed glycans demonstrated that D-arabinose but not alpha-D-glucose or D-mannose, led to the dispersion of the large clumps formed by the bacilli in stationary liquid cultures. These results confirm the presence of arabinose-containing glycans on the mycobacterial cell surface and demonstrate the implication of selective sugars in cell aggregation, suggesting that the clumping of mycobacterial cells is probably mediated by lectin-carbohydrate interactions.