Background: Cystic fibrosis (CF) is a multi-systemic disorder with an autosomal recessive inheritance. It is characterized by recurrent pulmonary infections and gastrointestinal problems, particularly pancreas insufficiency. Objectives: The aim of this study was to evaluate growth peptides in CF patients. Methods: This cross sectional study was approved by Mashhad University of Medical Sciences ethical committee. Patients were between six months to 18 years old, who were referred to Dr. Sheikh Hospital subspecialty clinic. They were enrolled for the study after obtaining a written constant. Demographic data was recorded. Of all cases, 10-cc blood sample was obtained and growth peptide levels were determined and measured. Data were analyzed by SPSS version 16 and Mann Whitney and χ2 tests were used. Results: Patients’ mean age at onset was 3.4 ± 1.1 months. Overall, 36 (60%) children were male and 24 (40%) were female. Mean body mass index (BMI) was 15.9 ± 3.2 kg/m2. Mean levels of growth hormone was 1.9 ± 0.37 (ng/mL), insulin-like growth factor 1 (IGF1) was 85.8 ± 9.6 microg/L and insulin-like growth factor binding protein 3 (IGFBP3) level was 18538 ± 10643 pg/mL. Conclusions: The mean serum levels of GH, IGF1, and IGFBP3 in CF children with growth failure was lower than children without growth failure. Regarding the relatively high prevalence of growth disorders in children with cystic fibrosis, selected, appropriate, and standard medical treatments could improve the outcome for these children.