We describe the effect of polymeric additives on the molecular gelation of two N-functionalized dipeptides. Hydrogelation was triggered by the addition of aqueous solutions to the dipeptide in DMSO. Gels can be formed in the presence of high concentrations of additives. The rheological properties of the gels are also remarkably tolerant to the presence of polymeric additives. When dextrans were used as additives, the effect on the rheological properties was determined by the viscosity of the dextran solutions. Examining a range of other polymer additives, it is clear that polymer structure is also an important parameter.