Introduction: Calcium and vitamin D are the cornerstone in treatment and prevention of osteoporosis as recommended by several guidelines. The efficacy of this combination regimen is limited due to poor adherence to the prescribed medication. Aim: This study aimed to assess patient’s adherence and persistence to Calcium and vitamin D supplements and to address reasons for non-adherence. Methods: This is a prospective quantitative survey, included patients who were attending a secondary care rheumatology clinic in a teaching hospital. Recruitment period was between April and June 2014. Patients were verbally asked before distributing the questionnaire about the duration of use of Calcium and vitamin D supplements, and the reason for prescribing it. Results: Regarding adherence score, the difference between calcium and vitamin D groups was not statistically significant (p=0.175). About one-third of patients in the two groups showed low adherence; 31% (53/171) and 38.2% (128/335) in calcium and vitamin D groups respectively. Age showed to influence adherence as the difference in scores between the two groups was significant (p=0.001). The younger patients (18-39 years) reported lower adherence to both medications. The educational status did not show a significant effect on adherence. The most frequently reported reason for non-adherence in both groups was “Forgetting to take medication” (29.5%, 89/302). About 25% of the patients stated that the reasons behind their non-adherence are multi-factorial. Conclusion: Low rates of adherence to Calcium and vitamin D supplements were reported among patients in the two treatment groups. The difference in adherence rate among these two groups was not significant.