The present study included a total of 75 bacterioscopically-negative leprosy patients in the phase of clinical regression of the disease presenting with specific lesions in the peripheral neural system and locomotor apparatus of different severity. Determination of serum alpha-1 anti-trypsin (α1-AT), alpha-2 acid glycoprotein (α1-AGP), alpha2-macroglobulin (α2-MG), and haptoglobin (HG) levels revealed that the acute-phase response of leprosy patients reflects the severity of the pathological process. The decreasing level of α2-MG and the concurrent increase of α1-AGP suggests the impairment of reactive reserves of the organism and should be regarded as an unfavourable prognostic feature predisposing to the development of complications of the leprotic process or a relapse of the disease. Parallel monitoring serum α1-AT, α1-AGP, α2-MG, and haptoglobin levels in bacterioscopically-negative leprosy patients presenting with complications of specific polyneuropathy makes it possible to control the clinical course of these conditions, predict their exacerbation, and prevent further progress of disturbances in the locomotor apparatus. Moreover, their tendency to cause the incapacitation and medico-social dysadaptation of the patients can be counteracted by the adequate correction of the rehabilitative treatments.