The enthalpies of solution of 2,4,6,8-tetramethyl-2,4,6,8 -tetraazabicycl o [3.3. 0] octane- 3,7-dione or tetramethyl-bis-urea (the drug Mebicarum) in formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, N,N,N',N'-tetramethylurea, and acetone were measured at 298.15 K. Standard enthalpies of solution and transfer from one solvent to another were computed. The enthalpies of solution of the solute were found to be endothermic and weak depending on the nature of methylation in an amide molecule. It was concluded that the solvent proton-donor ability and existing steric hindrances for H-bonding and other interparticle interactions play the key role in solvation of tetramethyl-bis-urea. (C) 2007 Elsevier B.V. All rights reserved.