Introduction Laryngomalacia (LM) is one of the most frequent congenital laryngeal anomalies in children and it has been associated with sleep disorder. Our main objective was to describe the sleep study findings in children with LM using polysomnography (PSG) or respiratory polygraphy (RP). Materials and methods We studied 18 children diagnosed with laryngomalacia by flexible nasolaryngoscopy. We performed a sleep study: PSG or RP and complete medical history on all of them. Results 18 children were studied, 5 by PSG and 13 by RP. 11 (61.1%) of them were females, with a mean age of 3.38 ( ± 3.01) months and weight 4674 ( ± 1418) g. LM type 1 was present in 7 (38.9%), type 2 in 6 (33.3%) and type 3 in 5 (27.8%) children. Premature birth described 4 (22.2%) children. Stridor was the most frequent symptom, in 15 (83.3%) followed by feeding difficulties in 8 (44.4%). Apneas were referred in 7 (38.8%), intercostal retraction and regurgitation in 6 (33.3%). Gastroesophageal reflux disease was confirmed in 10 (55.5%) by pHmetry requiring surgery in 2 cases. Echocardiography was performed in 14 (77.8%) showing cardiac anomalies in 4 (22.2%). In the sleep study the mean values were: sleep efficiency 83% ( ± 5.85), NREM% 36.9 ( ± 11.1), REM% 30.5 ( ± 7.7) and indeterminate 32.4% ( ± 18.2), apnea-hypopnea index (AHI) 13.74 ( ± 10.90), hypopnea 30.5 ( ± 48.2), obstructive apneas 58.8 ( ± 67.3), central apneas 13.6 ( ± 20.8), cumulative percentage of time spent at saturation ± 4.72), mean oxygen saturation 96% ( ± 1.94) and heart rate 126 ( ± 14.24) bpm. 16 children (88.8%) were diagnosed with sleep-disordered breathing (SDB). Conclusion Our findings confirmed the necessity to do a sleep study in children with laryngomalacia, regardless of the type of laryngomalacia in nasolaryngoscopy. Acknowledgements The authors would like to thank Dra. Navazo Eguia and the Sleep Unit staff at the Universitary Hospital of Burgos for their help.