Differential cross sections (DCSs) and Stokes parameters for electron impact excitation of 3s3p 1P1, 3s4p 1P1 states in magnesium are calculated by using the fully relativistic distorted-wave (RDW) program REIE06. In the calculations, the relativistic effects and electron correlations are considered systematically. The results are analyzed and compared with available experimental data and theoretical calculations, and they are in good agreement with each other.