Aggregatibacter (Actinobacillus) actinomycetemcomitans is a capnoic gram negative coccobacilli known to produce juvenile periodontitis. This organism was isolated in pure culture from an unusual case of osteomyelitis of the mandible. The patient was treated with tetracycline, which is the drug of choice for A. actinomycetemcomitans and the clinical response improved. From our limited review of the literature, it appears that this is the first case of osteomyelitis due to A.actinomycetemcomitans reported in India.