The study was conducted to evaluate compliance of antibiotics prescribing in three selected outpatients healthcare facilities in Papua New Guinea(PNG), to the country specific Standard Treatment Guidelines(STG)and to identify factors influencing prescribing pattern. The study was carried out in the Losuia Health Centre (LHC), Alotau Provincial Hospital and Port Moresby General Hospital (PMGH) outpatient departments. The study sample involved300participants at each setting. Oral amoxicillin products, chloramphenicol and co-trimoxazole made up approximately 70% of the antibiotics prescribed to 637/1090 of patients. Almost one-quarter (24.4%) of prescriptions for antibiotics were non-compliant selections. At the LHC approximately 20% of both dosage and duration errors occurred. Overall non-compliant prescribing for children was approximately 50% but significantly more compliant at PMGH (P= 0.0058) contrasting with the other settings. At the LHC only 30.6% of antibiotic prescriptions for children were compliant with STG requirements and fulfilled PNG regulatory requirements. With respect to the STGs, Community Health Workers (68.0%) and Nurse Officers made more non-compliant antibiotic selections. High levels of antibiotic prescribing combined with high levels of non-compliant antibiotic prescribing as compared to PNG-STGs, were identified in this study. This is a disturbing finding as it raises many questions related to quality assurance of health care interventions in PNG. The data also raises a clinical concern for the high level of oral chloramphenicol prescribed in out-patient settings.