The aetiology of GS remains obscure and a little is known about the immune competence of these patients. Interestingly, all children with OOGS were from low 'socio-economic status' and showed diminished delayed hypersensitivity reactions and reduced T cell counts (E-R) in our previous observation. We present herewith a preliminary data on evaluation of T cell sub-populations determined by monoclonal antibodies (CD3, CD4, CD8 and CD16 cells) in 10 patients with OOGS and AML prior to treatment. Quantitative immunoglobulin determinations of IgA, IgM, IgG were also made. The percentage of Pan T (CD3), CD4, CD8 cells were significantly lower than those in the controls (p < 0.01). The immunoglobulin levels were slightly elevated suggesting normal B cell functions. In conclusion, these preliminary findings suggest that cellular immune deficiency may be an underlying cause.