Basic values of g-tensor and Azz component of HF tensor of 2 spin labels and spin probe on HSA [human serum albumin] and nitroxyl radicals HO-15, HO-34 in the solvents of different polarity were measured by 2 mm band ESR of 2 mm range. Magnetic-resonance parameters of liophylized and water-solved spin-labeled HSA were shown to correspond to the parameters of the solvents of the label HO-15 and HO-34 in ethyl alcohol and water. A conclusion was drawn concerning the identity of the microenvironment of the nitroxyl fragment of liophylized HSA and frozen solution of the label HO-15 and HO-34 in ethyl alcohol and solvatation of the nitroxyl fragment of spin-labeled HSA, and label HO-15 (HO-34) by water molecules.