The aim of this study was to investigate the knowledge, health beliefs and the knowledge sources of osteoporosis in Turkish males who are at risk of secondary causes of osteoporosis. One hundred and sixty men who had one of the systemic diseases or drugs which negatively affects bone metabolism were included in the study. Patients were asked to fill in a self-administered questionnaire which was modified from a validated questionnaire for Turkish female patients with osteoporosis. Twenty-two patients (15.7%) had never heard of a disease named osteoporosis. The mean score for general knowledge was 31.86 ± 20.56 (over 100 points). Only 20 (16.9%) patients had received information from a doctor. Seventy-three (61.8%) of the patients stated that osteoporosis may be seen in men and only 42 (35.6%) patients were aware that they had a risk factor for osteoporosis. Most of the patients were unable to identify significant risk factors. Statistically significant positive correlation was found between KOS and patients' education levels (r = 0.453, p < 0.01). The findings in our study show that Turkish men who are at risk of osteoporosis do not have sufficient knowledge about osteoporosis and its consequences. We conclude that low education level of our patients accounts for poor osteoporosis knowledge.