Low-molecular-weight heparins undergo renal elimination, and therefore the proper dosing in hemodialysis (HID) patients is unclear. It was the objective of this study to evaluate the pharmacokinetic (PK) parameters of dalteparin in patients receiving chronic HID for end-stage renal disease. We performed a multidose PK study with prophylactic doses of dalteparin in twelve HID patients. Dalteparin 5,000 IU was administered subcutaneously daily for four consecutive days, with HID performed on day 2 and day 4. Anti-factor Xa activity was determined daily and at multiple blood samples after the 3(rd) and 4(th) dose. Eleven of 12 patients completed the study. The mean (range) PK parameters determined after the 4(th) dose were as follows: i) maximum concentration (C-max) was 0.31 IU/ml (0.06 to 0.55 IU/ml); ii) time to C-max. was 3.55 hours (2.59 to 4.96 hr); iii) area under the curve was 3.24 IU*hr/ml (0.64 to 6.44 IU*hr/ml); iv) half-life was 3.82 hr (2.03 to 9.63 hr); and v) trough anti-factor Xa activity 0.04 IU/ml (0.02 to 0.08 IU/ml). No major bleeding was observed. In general, patients with lower body weight exhibited a higher C-max. From this pilot PK study, we have determined initial PK parameters for dalteparin in HID patients. Although a standard prophylactic dose was used, we found that in this patient population differences in body weight influenced the C-max. Future studies to evaluate the PK parameters of dalteparin in patients receiving chronic HID may have to use weight-based dosing and will need to be performed over a longer period of time..