The paper presents a discussion on therapeutic results obtained with plasmapheresis treatment in 16 patients with stage II essential hypertension. Thirty-three comparable patients entered a control group of conventional treatment. The test and control patients with stage II hypertension were examined for time-course changes in T- and B-lymphocytes counts, the activity of the energetic enzymes (alpha-glycerophosphate dehydrogenase, succinic dehydrogenase, lactate dehydrogenase), serum immunoglobulins and circulating immune complex levels. It was established that the standard antihypertensive treatment failed to restore normal parameters of immunity and to favor positive alterations in the activity of the enzymes in the blood lymphocytes, whereas therapeutic plasmapheresis was found to stimulate immunity, especially cellular one. This occurred in line with a rise in the levels of lymphocytic dehydrogenases.