To describe unilateral and bilateral asymmetric sensorineural hearing loss in children and its etiological, audiological and demographic characteristics.Retrospective cross-sectional study developed in the Seção de Implante Coclear of Hospital de Reabilitação de Anomalias Craniofaciais, through the analysis of medical records.Data from 1152 patients were analyzed: 424 (37%) adolescents, adults or elderly, and 728 (63%) children, of whom 691 (95%) had bilateral symmetrical hearing loss, and 37 (5%) had unilateral hearing loss (n=10) or bilateral asymmetric (n=27) sensorineural hearing loss. The mean age at diagnosis of unilateral sensorineural hearing loss was 33.58±21.69 months, and for asymmetric bilateral it was 33.12±21.69 months, with a prevalence of 1.4% and 3.7%, respectively. The highest risk indicator for hearing loss for both groups was the family history of permanent deafness, which began in childhood. The majority of the relatives of children with unilateral sensorineural hearing loss presented the highest low socioeconomic classification (50%), while children with bilateral asymmetric sensorineural hearing loss were also be subdivided into upper (37%) and lower (37%).We observed a greater occurrence of asymmetric bilateral sensorineural hearing loss compared to unilateral hearing loss, as well as the hereditary risk indicator, with a predominance of the deep ear and female preponderance in both groups. Although neonatal hearing screening provides early identification of unilateral sensorineural hearing loss, the age at the audiological diagnosis is still above the recommended level. In addition, the majority of the children's family members presented a low level of income.