Aluminium (Al) compounds occur naturally in the environment and are used for different purposes such as water treatment, food additives and pharmaceuticals. Its potential toxicity on human has been documented but still the immunotoxic behaviour is debated. The current study aimed at exploring the effect of developmental exposure to Al on both cell mediated and humoral immunity on rats' offspring. Twenty pregnant albino rats in four groups (5 dams/group) were orally exposed to aluminium ammonium sulphate in 50, 100 and 200 mg/kg/ day in addition to a control group for five days a week during conception, pregnancy, lactation till weaning of pubs. Then forty female offspring of the treated mothers in four  groups (10 rats each) were maintained with the same Al doses whenever they can be directly dosed until reached 8 weeks old(near adults) so all critical windows of immune development were examined. Total body weights, spleen and thymus relative weights along with total and differential leukocytic counts were evaluated for juvenile rats. Three immunoglobulins (IgG, IgM, and IgE) in addition to two cytokines, interferon- δ (IFN-δ) and tumor necrosis factor- α (TNF-α) were measured as indicators of humoral and cell mediated immunity. Results indicated reduced body weights by dose increment and this was concomitant to increase in relative thymic and splenic weights. The concentration of TNF-α and IFN-δ were elevated especially with highest Al dose but other immunoglobulins, IgG and IgM showed insignificant change versus controls while IgE displayed decline in its level most observed with maximum dose group compared to controls. Total white blood cell count did not change significantly from controls but relative lymphocytosis was observed. The present results proved the developmental immunotoxic effect of the aluminium compound investigated, mainly of cell mediated type.  Further research is needed to examine specific critical stages of immune development in response to Al exposure as well as differential gender susceptibility