Serum immunoglobulin and immunoglobulin G subclasses were measured in thirty children with histologically proven allergic colitis and twenty age matched controls. Serum immunoglobulin A (mean +/- sd) (0.45 +/- 0.25 vs 87 +/- 0.41 Gm/L), IgG2 (29.2 +/- 13.1 vs 49.5 +/- 12.8 mg/dL), and IgG4 (7.58 +/- 3.01 vs 11.2 +/- 2.59 mg/dL) were significantly lower in allergic colitis than in the controls respectively (p < 0.001). There was a significant elevation of serum IgE in those with allergic colitis (p < 0.01). The serum IgG1 and IgG3 levels were not significantly different in allergic colitis and the controls (p > 0.10). Immunoglobulin A, IgG2 and IgG4 subclasses were low in 43.3%, 75.0% and 55.0% of cases of allergic colitis respectively, compared to 5.0% of the controls with low IgG2 and IgG4 (p < 0.005). The IgG1 and IgG3 subclasses were normal and comparable in both groups. Children with food allergic colitis in this study have low levels of IgG A, IgG2 and IgG4 subclasses. IgA, IgG2 and IgG4 subclass deficiency probably have a role to play in the pathogenesis of allergic colitis an mucosal immune defense mechanism.