In this study, we collected and analyzed PSG data to investigate that value of polysomnography (PSG) in diagnosing sleep problems in children. The results of PSG studies of children (< 18 years old) with sleep problems conducted from April 2015 to May 2017 at a children’s hospital in Taiwan were collected and analyzed retrospectively. Data for 310 patients (209 males and 101 females) who underwent PSG were collected. The final diagnoses were as follows: obstructive sleep apnea in 159 (51.3%), snoring in 81 (26.4%), limb movement sleep disorder in 25 (8.1%), hypersomnias in 12 (3.9%), central apnea in 8 (2.9%), enuresis in 7 (2.3%), bruxism in 5 (1.6%), sleep terrors in 5 (1.6%), narcolepsy in 3 (1.0%), sleep seizures in 3 (1.0%), sleep walking in 1 (0.3%), and insomnia in 1 (0.3%). PSG may help detect significant sleep-related problems in children and is useful for making therapeutic decisions regarding children. Obstructive sleep apnea syndrome (OSAS) was the primarily sleep problem for most of the children (51.3%); however, only 7.4% of them underwent surgery for OSAS, even though those with OSAS underwent surgery without undergoing PSG. We therefore suggest that children with sleep problems should undergo PSG.