Class 31

Class 31 may refer to:


 * British Rail Class 31
 * EAR 31 class
 * GER Class N31
 * HSH Class 31
 * L&YR Class 31
 * NBR Class M 4-4-0, later LNER Class D31
 * No.31-class patrol boat
 * Seibu Class E31
 * South African Class 31-000