Infants born from mothers with antiphospholipid antibody (aPL) -positive autoimmune disease were prospectively evaluated for anticardiolipin and anti-beta2 glycoprotein I antibodies (group 1) and for growth and neurological development. The results were compared with those obtained from two age-matched control groups (group 2 and 3). All infants were negative for anticardiolipin at 12 months of life, whereas 14 (63.6%), eight (33.3%), and 10 (55.5%) of infants from group 1, 2, and 3, respectively, were positive for anti-beta2 glycoprotein I. At follow-up, all infants had normal growth and neurological development. No thrombotic complication was observed. The negativity of anticardiolipin in all infants at 12 months suggests that anticardiolipin detection is the best assay to evaluate the disappearance of maternal aPL and to estimate the potential risk of thrombosis associated with these antibodies. The high rate of anti-beta2 glycoprotein I positivity in all three groups of infants may indicate that the synthesis of this antibody is stimulated by aspecific factors.