Most cases of mycobacterial lymphadenitis in children are caused by non-tuberculous mycobacteria, previously called the atypical mycobacteria. It is important to differentiate non-tuberculous mycobacterial lymphadenitis from tuberculous lymphadenitis as the treatment is different. We reviewed 19 children (12 girls and seven boys) with non-tuberculous mycobacterial lymphadenitis to define likely presenting features, helpful diagnostic measurements, and optimum management. Mean age at diagnosis was 5.2 years. Most had no systemic upset and clear chest x ray films. Cervical nodes were the commonest affected, and enlargement was usually unilateral. Mean duration of swelling was 6.6 weeks, and 63% of the nodes had an appearance suggestive of cold abscess. Routine haematology was unhelpful, and standard tuberculin testing performed in 47% yielded negative results in two thirds. Differential Mantoux testing with human purified protein derivative and an avium-intracellular antigen may be more useful. Antituberculous drugs were ineffective. The organism was usually highly resistant. Total excision is the treatment of choice. Antituberculous drugs are unnecessary.