BACKGROUND Chronic Leg Ulcer (CLU) is a common problem in our environment that poses huge economic and psychological challenges to individuals and their family members when it occurs. Venous insufficiency has been found to be the commonest cause of chronic leg ulcers in developed countries while trauma is more common in our environment. It is therefore appropriate to assess the vascular status in these patients. The Ankle Brachial Pressure Index (ABPI) using a hand held Doppler is the standard method of arterial assessment. However, an alternative method of this important assessment is the Lanarkshire Oximetry Index (LOI) that uses a pulse oximeter which is readily available. This study is to determine the reliability of this Lanarkshire Oximetry Index (LOI) in assessing the arterial status in comparison with Ankle Brachial Pressure Index (ABPI) in patients with chronic leg ulcer. MATERIALS AND METHOD This is a prospective study carried out for one year at the National Orthopaedic Hospital, Igbobi, Lagos. Sixty patients who consented and met the inclusion criterion were enrolled into the study. The relevant pressures were taken using the hand held Doppler and the pulse oximeter for calculation of ABPI and LOI respectively for each lower limb. The data obtained were analyzed using Statistical Package of Social Sciences (SPSS) Version 20. Further statistical relationships between the values were also determined. RESULTS The findings from lower limbs of sixty patients were analyzed out of which four left lower limbs and five right lower limbs were excluded. Most of the patients were of the age group 36- 45 years (30%). All the patients had some level of education with secondary level predominating (46.7%). Thirty five (58.3%) of them were overweight. The most common aetiological factor in these patients was venous disease 38(63.3%) followed by trauma 33(55%). A major number (81.1%) of the limbs had ABPI within the normal limit of 1.0 to 1.3, while 18% had low ABPI of between 0.8 and 0.9. One patient (0.9%) had a high ABPI of 1.4. The prevalence of peripheral artery disease (PAD) using Doppler ABPI was 18% (CI 11.4-26.4%) while with LOI was 22.7%. The Pearson correlation coefficient scores of LOI and ABPI correlated r=0.619 with P<0.001. The Bland-Altman’s plot qualified the level of agreement between LOI and ABPI as adequate (t =0.962; P= 0.338). There was substantial agreement (κ = 0.638) between LOI and ABPI in assessing arterial status. The sensitivity of LOI compared to the ABPI in this study was 80 % (CI 56.3-94.3%) while the specificity was 90.0 % (CI 82.1-95.4%). The positive predictive value was 64 % (CI 42.4-82.0%) while the negative predictive value was 95.3 % (CI 88.5-98.7%) for LOI. CONCLUSION This study confirms a good correlation between LOI and ABPI in assessing the arterial status in patients with chronic leg ulcers. Hence, LOI can be regarded as a suitable alternative tool in evaluating arterial assessment of CLU patients.