Severe Combined Immunodeficiency (SCID) represents a group of disorders characterised by impairment in both cellular and humoral immunity. SCID patients usually present severe and life- threatening opportunistic infections from early infancy . T-B-NK + SCID is a subgroup of SCID, which is an autosomal recessive disease, 50% of which is identified to cause by mutations in recombination activating genes (RAG1 and RAG2) . Mycobacterial infection after Bacillus Calmette-Guerin (BCG) vaccination is a rare disorder, occurring mostly in patients with immunodeficiency, in some cases, this may even lead to death. We reported a case of successful handling of BCG infection in a 6-month-old girl with T-B-NK + SCID caused by a novel mutation in RAG2 gene.