Abstract We conducted a study of Mantoux reactions in children managed for tuberculosis (TB) at the University of Maiduguri Teaching Hospital (UMTH) over a period of 4 y. Of the 97 eligible children managed for various forms of TB on whom a Mantoux test was conducted, 82 (84.5%) had a negative Mantoux reaction and 15 (15.5%) had a positive reaction. No statistically significant difference was found in relation to age groups and sex between the patients with positive and negative Mantoux reactions (p = 0.602 and p = 0.484, respectively). No significant difference in Mantoux reaction was observed among BCG-vaccinated and non-vaccinated children (p = 0.321). Although malnutrition and HIV infection were significantly associated with a negative Mantoux reaction, disseminated TB was not associated. We therefore recommend proper clinical assessment and other investigations for the diagnosis of TB in children in settings with a high prevalence of HIV infection and malnutrition, as Mantoux reaction results may be unreliable.