Objective. Conformational protein changes may be an important component of the disturbance of molecular processes in the development of pathological process in the body. We studied conformations of albumin molecule in the blood of patients with depression using biophysical –nanotechnical approach. Material and methods. We examined 19 patients with depression and 25 healthy controls. Properties of serum albumin were compared in patients with typical melancholic depression and controls using spectroscopy (subnanosecond range) with K-35 fluorescent probe. Results and conclusion. The properties of albumin binding sites in patients before and after treatment differed from those in controls. The authors suggest that it points to the changes in albumin molecule conformation that may influence the functional state of the protein. It has been suggested that these changes may be considered as biomarkers of pharmacotherapeutic efficacy.