Effect of a uniform magnetic field on the solid/liquid interface curvature and macrosegregation in directionally solidified the Al-0.85 wt.% Cu alloy has been investigated. Results show that the interface curvature and macrosegregation increase to a maximum when B is about 0.1 T; and then decreases as B still increases. This is good agreement with the computed velocities of the thermoelectric magnetic convection. Above results reveal that the uniform magnetic field induces the new convection and further modifies the interface curvature and macrosegregation. (C) 2011 Elsevier B.V. All rights reserved.