AIMS: To assess the clinical and pathological features of atypical mycobacterial lymphadenitis in childhood to define the salient clinical and histological features. METHODS: 17 cases were included on the basis of positive culture or demonstration of bacilli of appropriate morphology and staining characteristics. RESULTS: The mean age at diagnosis was 4.86 years. All children were systemically well, with clear chest x rays. Unilateral cervical lymphadenopathy was the commonest mode of presentation. Differential Mantoux testing played no part in diagnosis. Clinical diagnosis improved with awareness. Treatment varied with surgeons opting for excision and paediatricians adding six months antituberculous chemotherapy. Acid- and alcohol-fast bacilli were identified in nine cases. Bacterial cultures were conducted in 16 cases and were positive for atypical or nontuberculous mycobacteria in 14, the main organism being M avium-intracellulare complex (11 cases). Histologically, 12 cases had bright eosinophilic serpiginous necrosis with nuclear debris scattered throughout the necrotic foci. Langhans type giant cells featured in the majority of cases but infiltration by plasma cells and neutrophils was not consistent. CONCLUSIONS: Atypical mycobacterial lymphadenitis of childhood represents a rare but significant disease with characteristic clinical and histological features.