Background: Adherence to therapies is a corner stone of treatment success. Medication non adherence in geriatric patients leads to substantial worsening of disease, increased health care costs and death. A variety of factors are likely to affect adherence. Barriers to adherence could be addressed for each patient to deal with.  Objective: To assess the determinant factors of medication adherence in old patients living in their own houses. Methods:  This is a cross-sectional study of random sample of 438 geriatric patients where aged 70-85 years -old , living in their own homes in Serse Elian City , Menoufia Governorate . Patients' information were collected from the prescriptions in the file of the patient and home visits were done to examine their daily drug consumption. Results: Male geriatric patient were found to be more adherent to their medications than female (63.9 % versus 36.1%). Functional complain, living alone, low perceived health, cognitive impairment and patients satisfaction of their management plan were found to be significant factors in restrict following their prescribed drugs. Conclusions: Medication non adherence is not a rare event in elderly patients and is associated with functional complains and cognitive impairment.