The nutritional and biochemical parameters of 15 chronic hemodialysis (HD) patients with severe secondary hyperparathyroidism who had undergone total parathyroidectomy (PTX), with a forearm implant, were retrospectively studied at 1, 3, 6, and 12 months pre- and post-PTX. The concentrations of serum calcium and phosphorous significantly decreased in the first 6 months post-PTX. The concentration of blood urea nitrogen significantly increased at 6 and 12 months post-PTX. In contrast with control chronic HD patients who had no weight gain after nonparathyroid surgery, there was a progressive weight gain leading to a significantly higher dry weight at 12 months post-PTX. There was no significant change in serum potassium, albumin, cholesterol, transferrin, bicarbonate, hematocrit, normalized protein catabolic rate (nPCR), or erythropoietin dose at any time point post-PTX. The biochemical parameters of the 8 patients who had more than 5% weight gain, during 12 months post-PTX, were not statistically different from the remaining 7 cases who had weight gain less than 5% (or had lost weight) in the same time period. The same was true for 4 patients with weight gain of more than 10% versus the latter group. In conclusion, HD patients with severe secondary hyperparathyroidism are prone to progressive weight gain post-PTX, which reaches significance by the twelfth month. In 53% of the patients, the weight gain is more than 5% above the baseline. The nutritional and biochemical parameters pre-PTX were not helpful in distinguishing those who developed significant weight gain post-PTX.