OBJECTIVES: Calcium and vitamin D supplements have been widely used and recommended for women to prevent or delay the onset of osteoporosis and the risk of bone fractures. Other benefits include the improvement of blood pressure and lipid levels and a lowering of body weight. In theory, the beneficial effects of calcium and vitamin D suggest improvements in cardiovascular health. Recent publications suggest the contrary and allude to increase serum calcium as a risk factor for adverse cardiovascular events. This study examines whether the exposure to these supplements are associated with cardiovascular events. METHODS: The study was based on California Medicaid (Medi-Cal) fee-for-service administrative claims data from January 1995 to December 2002.  The study population consist of patients >50 years with recorded diagnoses of osteoporosis followed from diagnoses date to the end of eligibility. Patients were excluded for prior use of the supplements or diagnosis of cardiovascular events or drug induced osteoporosis. Propensity score matching based on age, gender, elixhauser comorbidities and eligibility data created case (n= 1594) and control groups (n=4782). Chi-square analysis was conducted for comparison of the cardiovascular events defined as ICD9 codes for myocardial infarction and searchable terms of “cerebral infarction, hemorrhage, ischemia” for stroke. RESULTS: No statistically significant relationship was found between the study groups for stroke (p=0.56) and myocardial infarction (p=0.54). Components of stroke included cerebral artery occlusion (p=0.94), precerebral artery occlusion (p=0.27), intracerebral hemorrhage (p=0.23), and subarachnoid hemorrhage (p=0.05).  The clinical benefits of the supplements were evident with subarachnoid hemorrhage with 0 recorded diagnoses in the case group compared to 12 recorded diagnosis in the control group; however statistical significance was not established. CONCLUSIONS: The use of calcium and vitamin D supplementation yielded no relationship to the risk of adverse cardiovascular events. Moreover, no broad cardio-protective effects can be concluded from the study.