Osteoporosis becomes increasing problem in adolescents and adults patients with cystic fibrosis (CF). Inadequate bone mineralization in childhood and adolescent period in these patients results in reduced bone density and fractures. The aim of the study was to determine prevalence and associated risk factors of osteoporosis in children and adults with CF in R.Macedonia. The study included 30 CF patients (16 males) with main age 11,6 +/− 4,5 years and 15 healthy subjects at same age. Quantitative ultrasound sonometry (QUS) was used to determine bone status. The results were presented as Z score, how many standard deviations differ from normal values for age and sex. The mean values of Z score for QUS parameters for CF group were: speed of sound (SOS) = −0,17+/−1,4; transmission index (TI) = −0,6 +/−1,1 and osteosonoassesment index (OSI) = −0,5 +/− 1,2. They were decreased significantly (p<0,001) compared to control group. Ten CF patients (33,3%) have reduced bone density, 8 have osteopenia, and 2 osteoporosis. Disease severity, decreased FEV1 and decreased 25 OHD in patients with CF were strongest predictors of decreased QUS parameters. The values of correlates were for T/V (r = 0,6); for serum levels of 25 OHD (r = 0,48); for FEV1 and FVC (r = 0,48) and for Shwachman-Kulczyski (S-K) clinical score (r = 0,52). In our CF population there are patients with reduced bone density. The diagnosis and treatment of osteoporosis in individuals with CF has to improve the quality of life for these patients.