The rationale and objectives of the study were to evaluate the influence of the experimental conditions (buffer, salt, etc.) on the data characterizing the non-covalent interaction between MRI contrast agents and human serum albumin and hence their in vivo relaxivity. The interaction of three gadolinium contrast agents (Gd-EOB-DTPA, Gd-BOPTA and MP-2269) with human serum albumin was assessed through the measurement of proton relaxation rate enhancement in various experimental conditions. The data show the negative effect of halide salts on the paramagnetic relaxation enhancement of the three contrast agents. The presence of halide salts can thus have a negative effect on the efficacy of MRI contrast agents interacting with HSA. In addition, careful attention must be paid to comparisons of the binding parameters of various contrast agents reported in different studies since the composition of the medium can greatly influence the non-covalent interaction.