BACKGROUND The epidemiology and management of nontuberculous mycobacterial (NTM) infection in Australian children is unknown. METHODS From July 2004 to June 2007, clinicians identified children with NTM infection as part of a nationwide active surveillance network. Following notification, detailed data were collected. RESULTS From 192 reports, data were received on 153 cases (response rate: 79.7%). Of these, 102 met inclusion criteria. The median age was 2.9 years. Predisposing conditions were infrequent and included chronic respiratory disease (n = 12) and immunosuppression (n = 6). Lymphadenitis was the most frequent presentation (n = 68) with pulmonary and disseminated disease infrequent (n = 14 and 3, respectively). NTM was isolated in 68 cases with Mycobacterium avium-intracellulare complex most frequently isolated (33/68; 48.5%). Surgery was performed in 78 cases and 42 children were treated with antimycobacterial therapy. Twenty-five subjects received surgery and antimycobacterial therapy. Follow-up data were available for 77 children with recurrence observed in 18 cases. Complete excision was associated with a higher rate of treatment success when compared with all other therapies (OR: 9.48 [95% CI: 2.00-44.97], P = 0.001). Mycobacterium lentiflavum infection accounted for 4.4% of culture confirmed cases and had a lower rate of treatment success than other species (0% vs. 78.2%; P = 0.016). CONCLUSIONS The incidence of NTM infection in Australian children is 0.84 of 100,000 (95% CI: 0.68-1.02). Infection occurs most often in young children without predisposing conditions. Despite therapy, there was recurrence in 23.4% of cases.