['It has been reported that hemodialysis (HD) stimulates hepatocyte growth factor (HGF) release, but it is not clear if this stimulation is due to HD itself or to heparin used during HD. To clarify this issue, we undertook the present study.', 'We studied 18 HD patients using high-flux dialyzers, during a single 4-hr hemodialysis session (session A). The dialyzers were pre-rinse with normal saline without heparin, and HD was started with zero ultrafiltration and without anticoagulation. Anticoagulation was administered as IV injection (80 IU/kg of LMWH enoxaparin sodium) 10 min after the beginning of HD. HD was continued for 10 more minutes and then as prescribed. HGF serum levels were measured before the beginning of the HD session (sample t0) as well as 10 and 20 minutes after the beginning of the session (samples t10 and t20). In six more patients (controls), the same study was repeated but without the administration of LMWH during the first 20 min of HD initiation (session B).', 'In comparison with t0, t10 HGF serum levels changed significantly in neither session A nor in session B. However, at t20, HGF levels increased significantly in session A compared with t0 (increment 666.3 +/- 211.0%, p < 0.0001) and t10 (increment 894.2 +/- 506.0%, p < 0.0001), but not in session B. No differences were found between sessions A and B at samples t0 and t10 (p = NS). HGF serum levels at t20 in session A were found to be higher compared with corresponding levels in session B (p < 0.0001).'] Are elevated hepatocyte growth factor levels at the beginning of high-flux hemodialysis due to heparin administration?