Objective:To analyze the clinical and genetic characteristics of congenital hypogonadotropic hypogonadism (CHH) in boys.Methods:Cross-sectional study.Clinical data, laboratory data and genetic results of boys who were genetically diagnosed with CHH at the Department of Endocrinology of Shenzhen Children′s Hospital from December 2019 to February 2023 were collected in this retrospective study.Their clinical manifestations, hormone levels and gene mutations were analyzed.The non-normal distribution was represented by the median.The rank sum test was used to compare the non-normal distribution data between the two groups.Results:A total of 27 boys were genetically diagnosed with CHH, with the age at first diagnosis ranging from 0.3 to 16.6 years old.All these children presented with micropenis (100%), of whom 16 were complicated with cryptorchidism (59.3%), 9 with microrchidia (33.3%), 7 with simple micropenis (25.9%), and no had simple cryptorchidism.Three children had cardiovascular dysplasia.The median of basal luteinizing hormone(LH) level was 0.09 IU/L, and 92.5%(25/27) of children had the basal LH level below 1.00 IU/L.The median of peak LH level after gonadotropin-releasing hormone(GnRH) stimulation was 1.42 IU/L, and 96.2%(26/27) of children had the peak LH level below 4.00 IU/L.The median of serum inhibin B was 41.15 μg/L, and the median of serum anti-Müllerian hormone(AMH) was 12.62 mg/L.The serum AMH level of children with cryptorchidism was significantly lower than that of children without cryptorchidism (10.02 mg/L vs.50.50 mg/L, P<0.05). A total of 12 gene mutations were detected in the 27 children, of which 1 was biallelic mutation.The most common gene mutations were in CHD7 and ANOS1 genes (7 children each, both accounting for 51.8%), followed by FGFR1 gene (3 children, 11.1%). After short-term treatment by GnRH pump or subcutaneous injection of recombinant human follicle stimulating hormone in 4 children, the levels of serum inhibin B and AMH increased significantly, and the testicular volume also increased. Conclusions:CHH is a congenital disease with different clinical manifestations at different ages.The main manifestations in childhood are micropenis and cryptorchidism, and some children have microrchidia.Its diagnosis in prepuberty is difficult, but genetic testing is of great significance for early diagnosis.