Hypertension is a global health problem and affects more than one billion people worldwide. Long term hypertension is associated with grave complications and therefore maintaining blood pressure within normal range is essential and ensuring patient's drug compliance is an important sector of patient care. Therefore, the purpose of our study was to find out the causes of poor compliance to antihypertensive medications. This cross sectional study was carried out in Medical Department of Ayub Teaching Hospital Abbottabad, Pakistan from 1st September 2017 to 30th October 2018. One hundred ninety three (193) patients were included through non probability consecutive sampling and were divided into two groups on the basis of compliance. The data was collected with the help of a structured questionnaire and analyzed using SPSS 20. Out of 193 hypertensive patients, 88(45.6%) were male while 105(54.4%) were females, with minimum age of 24 years and maximum age of 95 years and mean age of 61.98±12.81SD. Minimum duration of hypertension was 5 months and maximum was 30 years with mean duration of hypertension and standard deviation (SD) of 6.26±6.51 years. One hundred & Twenty (62.2%) patients were non-compliant, while 73(37.8%) were compliant to medication. Forgetfulness of medicine 85(70.8%) and non-affordability 62(52.5%) were the most common causes of noncompliance. This study documented a significantly higher proportion of medication non-adherence among hypertensive patients, with drug forgetfulness and affordability being found as the most common cause.