medication error has become a global problem. Medication administration that is error free is important in achieving positive outcomes in patient's care. This study assessed adherence to medication administration guidelines among nurses in a health facility in South-West Nigeria.a cross-sectional descriptive study was carried out on 75 nurses involved in oral medication administration. Data was collected using direct observation method with an observational checklist developed from literature. Data analysis was done using frequency, percentage, Mean and Standard Deviation. Test of relationship was carried out using Kruskal-Wallis Test and Mann Whitney Test at 0.05 (p<0.05) level of significance.almost an average (49.3%) of participants did not provide information about the medication. More than 1/3rd (38.7%) did not perform right assessment where necessary. The majority (76.0%) did not serve correct medication. Overall level of non-adherence was 48%. Adherence to medication administration guidelines was significantly related to age (χ2 = 9.673, p<0.05), marital status (χ2 = 9.426, p<0.05), years of experience (U=404.000 Z=2.7622, p<0.05), type of shift (χ2 = 6.314, p<0.05), nurses-patient ratio (χ2 = 11.598, p<0.05).some nurses did not adhere strictly to the guidelines of medication administration. Adherence to medication administration guidelines was related to age, marital status, years of experience, type of shift and nurse-patient ratio. Poor adherence to medication administration guidelines may jeopardize patient safety. There is need for development of a universal medication procedure/protocol and continuous education of nurses on medication administration practices.