Background: Evaluating prescription pattern is a measure of drug utilisation review to assess irrational or inappropriate drug use which remains a problem in health facilities. It involves assessing the prescribing, dispensing and distribution of medicines. Studies have shown that more than 50% of all medicines worldwide are incorrectly prescribed. Increased resistance of micro-organisms to antibiotics, drug-drug interaction due to poly-pharmacy are all attributable to inappropriate prescription. Objective: The purpose of the study was to evaluate the drug prescription pattern in the General Outpatient Department of a tertiary hospital in Port Harcourt, South-South Nigeria based on WHO prescribing indicators. Methods: A cross-sectional retrospective study was carried in the GOPD of the hospital. A total of 2000 prescriptions issued between January to December 2015 were systematically selected and reviewed using the WHO/INRUD prescribing indicators. Data collected were entered into Excel, 2013 and transferred to and analysed with SPSS Version 23 software. Results: Out of a total of 6797 drugs prescribed, the average number of drugs prescribed per encounter (ANDPE) was 3.4±1.5, 2411 (35.5%) drugs were prescribed by generic name while 4382 (64.5%) were drugs prescribed by brand names, 4163 (61.3%) drugs were prescribed from the Essential Drug List (EDL) of Nigeria. Observation from the collected data showed that 653 (32.7%) of the total prescriptions analysed contained one or more antibiotics while 29 (1.5%) had one or more injections. Other drugs prescribed include 416 (20.8%) antimalarials, 580 (29%) antipyretics and 475 (23.8%) antihypertensives. Conclusion:The study revealed poor compliance to the WHO core prescribing indicators: polypharmacy, poor antibiotics and injection use as well as lack of compliance to EDL prescriptions. There is need for adequate monitoring of prescription writing in the health facility in order to ensure rational drug use.