Background:Errors in consuming drugs are associated with significant morbidity and mortality, besides an impact on the already overburdened health-care system. Misunderstanding drug labels and prescriptions plays an important role in contributing to adverse drug events.Objective:To evaluate abilities to understand prescriptions and drug labels among patients attending tertiary care hospital in Karachi.Methods:A cross sectional study was conducted at the Aga Khan University Hospital (AKUH), from January to March 2009. After informed consent, 181 adult patients and their healthy attendants were interviewed at AKUH using a standardized questionnaire, which ascertained patient demographics, factors that might increase exposure to health-care personnel as well as the basic knowledge and understanding of prescriptions and drug labels.Results:Out of 181, majority 137(76%) had received graduate or post-graduate degrees. 16 (9%) had received no formal education; of which all were females and 89(84%) of the total females were housewives. Overall, 130(72%) followed only a single doctor's prescription. Majority failed to understand various medical terminologies related to dosage. In the high literacy group, 45(33%) understood once daily OD (p = 0.003), 27(20%) thrice daily TID (p = 0.05), 29(21%) twice daily BD (p = 0.01), 31(23%) thrice daily TDS (p = 0.002) and 43(31%) as needed SOS (p = 0.003) as compared to the group with no formal education, who were unable to comprehend the terms. The most common reason for using more than one prescription was decreased satisfaction with the doctor in 19(39%) and multiple co-morbids as responded by 17(35%) of patients. Knowledge regarding various medical terminologies used for dosage and routes of drug administration were also understood more frequently among the English medium respondents. The elderly identified medicine through color (47%, p<0.001), and were less likely to understand drug indications (p = 0.05) compared to younger subjects.Conclusion:Understanding of drug prescriptions is alarmingly low in the community, even amongst the educated. Care givers need to revisit this often ignored aspect of patient care.