PURPOSE: Family history of allergy and cord blood immunoglobulin E concentration have been proven to be predictors of the development of allergic diseases in children. The purpose of this study is to evaluate whether maternal, cord and baby's blood total eosinophils or eosinophil cationic protein (ECP) in addition to the above two predictors could be a predictor of subsequent allergic diseases later in life. METHODS: Fifty pregnant women and their newborns with positive family history of allergic disease and fifty other pregnant women and their newborns with no family history were investigated and a clinical follow-up study was conducted in thirty-two infants for two years. Immunoglobulin E level, total eosinophils and ECP level were measured in maternal, cord and baby's blood. RESULTS: The group who developed allergic disease showed significantly high cord immunoglobulin E concentration than the group who did not develop allergic disease (P<0.01). There were no significant differences of immunoglobulin E level, total eosinophils, ECP level in maternal, cord, baby's blood between the group with positive family history of allergic disease and the group with no family history. The incidence of allergic disease was significantly higher in the group which had both positive family history and high cord blood immunoglobulin E concentration than the group which had no family history and low cord blood immunoglobulin E concentration (P<0.01). CONCLUSION: Family history of allergy and high-cord blood immunoglobulin E concentration are the best predictors of allergic diseases later in life.