In a trial at determining the most relevant immunoglobulin isotype that could reflect success of praziquantel treatment, an ELISA using soluble egg antigen (SEA) was applied on sera of Egyptian patients suffering from active intestinal schistosemiasis without hepatic complications, determining the levels of IgE, IgA, IgM, IgG1, IgG2, IgG3 and IgG4 raised against the SEA, both, pre- and early post-treatment. The positive results obtained to all anti-SEA immunoglobulin isotypes before treatment support the usefulness of this technique in the diagnosis of schistosomiasis. Except for IgG3 subclass, a statistically significant correlation was found between egg output-reflecting intensity of infection- and the different immunoglobulin levels, especially anti-SEA IgG4. When repeating the assay 5-6 months after treatment, the immunoglobulin levels showed either a rise (in case of IgE) or a drop (in case of IgA, IgM & IgG1-4), all of statistical significance, yet, IgG1-4 were still positive. So, ELISA could not give a definite indication of cure after anti-bilharzial treatment. IgE, IgG2 and IgG4 were revealed to be the most significant immunoglobulin isotypes at the post-treatment level, both statistically and due to their implications on resistance/ susceptibility to re-infection and also due to the correlation of IgG4 with the tendency to develop periportal fibrosis. Conclusively, although not having defined a particular Ig isotype as marker for cure, yet it exposed the urge for early post-treatment determination of IgE and IgG4 isotypes, which could serve as markers for picking up high risk patients susceptible to reinfection or liable to develop bilharzial periportal fibrosis, and who might benefit from a second course of specific treatment.