OBJECTIVES:  The aim of this study was to assess drug use pattern in ten primary healthcare centers (PHCCs) of Bahawalpur, Pakistan by employing WHO/INRUD core drug use indicators. METHODS:  This was a descriptive, non-experimental and cross-sectional study. For the prescribing indicators, 1000 prescriptions (100 prescriptions per PHCC) were systematically sampled out of the total 290,000 prescriptions written during January to December 2014. A total of 300 randomly selected patients (30 per PHCC) and 10 pharmacy personnel (one per PHCC) were observed and interviewed to investigate the patient-care and facility-specific indicators, respectively. We used published ideal standards for each of the WHO/INRUD indicators. RESULTS:  Among the prescribing indicators, the average number of drugs per encounter was 3.4 (SD = 0.8) (optimal value = 1.6–1.8), the drugs prescribed by the generic name were 71.6% (optimal value = 100%), the encounters with antibiotic(s) prescribed were 48.9% (optimal value = 20.0–26.8%), the encounters with injection(s) prescribed were 27.1% (optimal value = 13.4–24.1%) and the drugs prescribed from the Essential Drugs List (EDL) were 93.4% (optimal value = 100%). Among the patient-care indicators, the average consultation time was 2.2 minutes (SD = 0.8) (optimal value ≥10 minutes), the average dispensing time was 38.0 seconds (SD = 12.1) (optimal value ≥90 seconds), the percentage of drugs actually dispensed was 90.9% (optimal value = 100%), the percentage of drugs adequately labeled was 100.0% (optimal value = 100%) and the patients’ knowledge of correct dosage was 62.1% (optimal value = 100%). Among the facility-specific indicators, all PHCCs had a copy of the EDL and the key drugs available in the stock were 82.0% (optimal value = 100%). CONCLUSIONS:  Irrational use of drugs was observed in all healthcare facilities. This study necessitates the need to implement WHO/INRUD recommended twelve core interventions to promote rational use of medicines.