non spesific reacrions to Casoni test were reported by several authors.Similar reports are avilable in literture concerning I.H.A.T in cases of schistosomiasis and hydatidosis.Therefore it was the objective of the present study to throw further light on the validity of serodiagnosis of these two important diseases.Results obtained denote a restricted cross reaction at low grade titres between the two diseases with both Casoni and I.H.A.T tests when using non spesific heterogenous antigen .It was concluded that serological reactions should be interpreted with caution especially in presense of other concamitant diseases.