OBJECTIVES: To compare initial in-hospital thromboprophylaxis and first treatment after discharge between 1998-2002 and 2003-2007, among patients receiving total hip replacement (THR) in the Netherlands.  METHODS: From the PHARMO database, all patients ≥18 years with a THR hospital admission between January 1998-June 2007 were selected. Patients with in-hospital pharmacy data, referred home after discharge, and a follow-up in PHARMO of ≥six months after surgery were included in the study cohort. RESULTS: Of the total 6,000 THR patients, 2,106 (35%) underwent surgery in 1998-2002 and 3,894 (65%) in 2003-2007. About one third of all patients were male and mean age was 68 years. Length of hospital stay decreased over time: in later years, 52% of THR patients were hospitalized for ≤one week compared to 17% of the 1998-2002 patients. Initial in-hospital thromboprophylaxis was mostly with LMWH: 66% of patients in 1998-2002 and 70% in 2003-2007. After the introduction of fondaparinux in 2003, the proportion of patients treated in-hospital with vitamin K antagonists (VKAs) or combination LMWH+VKAs decreased (13% to 6% and 18% to 3% respectively). After discharge, 53% of patients with a THR in 1998-2002 received VKAs and 17% were treated with LMWH. In contrast, 44% of patients from 2003-2007 received LMWH and only 9% were treated with VKAs at home. The proportion of patients receiving no antithrombotic treatment after discharge increased from 30% to 38%. CONCLUSIONS: In both five-year time frames, in-hospital thromboprophylaxis among THR patients was mostly with LMWH. First treatment after discharge shifted from primarily VKAs in 1998-2002 to LMWH in 2003-2007. Although guidelines recommend thromboprophylaxis for six weeks after surgery, our data show that in later years 38% of patients did not receive antithrombotic treatment after discharge. With an average hospital stay of 8 days, we can therefore assume a six-week treatment period is not common practice.