Mesoporous MCM-41 silicas anchored with sulfonic acid (–SO3H) groups (denoted MSN-SA) via postsynthesis modification are very effective for the Beckman rearrangement. A simple and convenient procedure for conversion of a variety oximes to their corresponding amides and lactams has been developed. The reaction was carried out in the presence of MSN-SA as the catalyst. The best results for conversion of oximes to amides and lactams were obtained in the presence of MSN-SA and solvent free condition at 110 ºC. Excellent yields were obtained from oximes with electron-donating and electron-withdrawing groups. The system also worked well with polynuclear aromatic, heterocyclic and aliphatic oximes.