To evaluate the significance of serum PTH (7-84) in hemodialysis patients, correlation of the serum PTH (7-84) level with various nutritional markers was investigated in HD patients. Serum PTH was determined in 170 male HD patients by either a Bio intact PTH assay or a second-generation intact PTH assay. The level of bone formation markers and bone resorption markers were also measured. Lean body mass in trunk region was measured by dual X-ray absorptiometry. The serum PTH (7-84) level was obtained for the difference between serum I-PTH and Bio-PTH. Serum PTH (1-84) was directly obtained from the serum Bio-PTH value. Serum PTH (7-84) correlated significantly with nutritional markers such as body weight, albumin, PCR, TAC BUN, BUN, phosphate and lean body mass in trunk, whereas PTH (1-84) only correlated with phosphate. The correlation of serum PTH (7-84) with bone metabolic markers was no less significant than that for PTH (1-84). The results suggest that serum level of PTH (7-84) may provide clinically useful information, not only of the bone metabolic state but also of the nutritional state in HD patients, in sharp contrast to the exclusive correlation of PTH (1-84) with bone metabolic state.