Collision strengths for electron impact excitation of fine-structure levels in sulfur-like Fe XI are calculated in a semirelativistic R-matrix approach. The 38 fine-structure levels arising from the 20 LS states 3s²3p⁴³P,¹D,¹S; 3s3p⁵³P^o,¹P^o; 3s²3p³(⁴S^o)3d³D^o, 3s²3p³(²P^o)3d^1,3P^o,^1,3D^o,^1,3F^o, 3s²3p³(²D^o)3d^1,3S^o,^1,3P^o,^1,3D^o,^1,3F^o are included in our calculation. The target levels are represented by configuration interaction wave functions. The relativistic effects are considered in the Breit-Pauli approximation by including one-body mass correction, Darwin term, and spin-orbit terms in the scattering equations. Collision strengths for transitions from the 3s²3p⁴³P_2,1,0 levels to the fine-structure levels of the 3s²3p³3d configuration are compared with the distorted-wave results of Bhatia & Doschek at 8.0, 16.0, 24.0 ryd. There are some significant discrepancies between the two calculations, mostly caused by the difference in target wave functions. The collision strengths are integrated over a Maxwellian distribution of electron energies to obtain effective collision strengths over the temperature range from 5 × 10⁵ to 5 × 10⁶ K.