Purpose: This study was done to identify the relationship among bone mineral density (BMD), body composition and osteoporosis self-efficacy and to identify predictors of BMD in female nursing students. Method: Participants were 154 nursing students. Osteoporosis self-efficacy was determined by a self-report questionnaire. BMD was measured by ultrasound bone densitometry and body composition by a body composition analyzer. Data were collected between April 1 and 27, 2013 and analyzed using descriptive statistics, ANOVA, Scheff$acute{e}$ test, Pearson correlation coefficient, and multiple regression with SPSS 18.0. Results: Mean BMD at the calcaneus site was $0.58{pm}1.31$ (T-score). Incidence of osteopenia was 11.7%. Percentage of body fat (PBF)-defined obesity had higher prevalence than body mass index (BMI)-defined obesity. BMD had significant positive correlations with skeletal muscle mass (r=.226, p=.005) and fat free mass (r=.225, p=.005). The factor predicting BMD was skeletal muscle mass with 4.7% of explained variance. Conclusion: Study results indicate that of body composition components, skeletal muscle mass is the prime predicting factor for BMD. Thus to promote healthy bones, it is important to strengthen the muscles using a program, based on balanced development of all muscles.