ABSTRACT Objective: To compare the patency of vascular access created for hemodialysis with and without the use of pre-operative Doppler ultrasound (US) vascular mapping. Setting: University of Santo Tomas Hospital, España, Manila. Materials and Methods: All adult patients with chronic kidney disease, either admitted or seen in the out-patient clinic and hemodialysis center from the months of February to September 2004, who will undergo permanent vascular access placement for hemodialysis for the first time, were randomized into two arms: with and without vascular mapping. Patients with previous arteriovenous fistula, graft and vascular surgery in the upper extremities were excluded from the study. The clinical profile of patients, the preferred type and location of vascular access of the surgeon before and after vascular mapping results were noted. The patency and complications of the vascular access with pre-operative vascular mapping were compared with those without vascular mapping. Results: Among 42 patients, 18 (43%) had preoperative vascular mapping and 24 (57%) underwent vascular access placement without vascular mapping. The clinical profile (age, sex and etiology of chronic kidney disease) was not statistically different between the two groups (p-value>0.5) using the Mann-Whitney U test for the age variable and Chi-square test for the remaining variables. Likewise, there was no significant difference in terms of the surgeon’s preference for the type and location of the vascular access between the two groups (p-value>0.05) using the Chi-square test. The vascular access of all patients who had pre-operative vascular mapping remained patent all throughout the study period. Among those without pre-operative vascular mapping, 4 (17%) had patency failure. The computed adjusted risk ratio or relative risk is 0.6, hence, vascular mapping is effective in ensuring the functional patency of vascular access for at least 8 weeks from the time of cannulation. Conclusion: There seems to be a beneficial effect in terms of patency of vascular access created for hemodialysis with the use of preoperative Doppler ultrasound vascular mapping based on the relative risk (RR 0.68).