Background: Parathyroid hormone (PTH) has an adverse effect on the immune system and may cause immunologic disorders in patients with chronic renal failure. The in vivo effects of a parathyroidectomy on the immunologic parameters was examined.Methods: Thirty-four patients under dialysis therapy received a parathyroidectomy (PTx) for secondary hyperparathyroidism (HPT). They were prospectively studied regarding serum immunoglobulins, complements, CD markers, and serum soluble IL-2 receptor (sIL-2R) until 12 months after PTx.Results: The serum levels of IgG, IgA and IgM showed significant increase until 12 months after PTx (P <0.001, respectively). C3, C4, and CH 5 0 also indicated significant increase at 12 months after PTx. In cellular immunity, only serum sIL-2R showed significant increase 2 weeks after PTx (P = 0.028). The hematocrit and serum albumin also improved significantly at 12 months.Conclusions: PTx showed beneficial effects on humoral immunological markers. The effects are probably due to the remarkable PTH reduction and partly improved nutritional state after PTx.