The structures of five substituted alpha,alpha'-trehalose trehalose derivatives have been determined, and these are compared with those of four previously published analogues. In 2,2',3,3',4,4'-hexaacetato-6,6'-bis-O-methylsulfonyl-alpha,alpha'-trehalose, C26H38O21S2, where the molecules lie across twofold rotation axes in the space group C2, a single C-H...O=S hydrogen bond links the molecules into sheets. 2,2',3,3',4,4'-Hexaacetato-6,6'-bis-O-(4-toluenesulfonyl)-alpha,alpha'-trehalose, C38H46O21S2, crystallizes with Z' = 2 in the space group P2(1)2(1)2(1) and a combination of three C-H...O hydrogen bonds, each having a carbonyl O atom as an acceptor, and a C-H...pi(arene) hydrogen bond link the molecules into a three-dimensional framework. 2,2',3,3',4,4'-Hexaacetato-6,6'-diazido-alpha,alpha'-trehalose, C24H32N6O15, crystallizes as a partial ethanol solvate and three C-H...O hydrogen bonds link the substituted trehalose molecules into a three-dimensional framework. In 2,2',3,3'-tetraacetato-6,6'-bis(N-acetylamino)-alpha,alpha'-trehalose dihydrate, C24H36N2O15...2H2O, the substituted trehalose molecules lie across twofold rotation axes in the space group P2(1)2(1)2 and a three-dimensional framework is generated by the combination of O-H...O and N-H...O hydrogen bonds. The diaminotrehalose molecules in 6,6'-diamino-alpha,alpha'-trehalose dihydrate, C12H24N2O9...2(H2O), lie across twofold rotation axes in the space group P4(3)2(1)2: a single O-H...N hydrogen bond links the trehalose molecules into sheets, which are linked into a three-dimensional framework by O-H...O hydrogen bonds.