This report presents the selected variables of a consecutive series of 1-10-year-old children with unilateral sensorineural hearing impairment (USNHI; defined as four-frequency pure-tone audiometry (PTA) 0.5, 1, 2, 4 kHz > or = 30 dB HL): severity, presumptive aetiologies, age at ascertainment, hearing aid acceptance, non-verbal intelligence, time of occurrence of first words and two-word utterances, size of vocabulary, and linguistic achievements. During a 4-year-period in a defined geographical area of Germany (Lower Saxony), 31 children were carefully audiologically and psychologically examined at the Department of Phoniatrics/Pedaudiology, University of Göttingen. All children were fitted unilaterally with a hearing aid. The HI was mild in 3%, moderate in 23%, severe in 29% and profound in 45% of the cases. The hearing defect was congenital in 23%, postnatally acquired in 16%, and of unknown onset in 61% of the cases. The affected side was the right in 17 cases, and the left in 14. The mean age at ascertainment was 65.5 months (SD 25.5; median 70). According to parental judgement, nearly 81% of the children had accepted their hearing aid (based on the daily/weekly time for which the child was using the hearing aid). On average, the children scored in the normal range in standardized non-verbal intelligence tests. They were delayed in using two-word phrases (on average for 5 months), but not in using their first words. However, children with USNHI experienced no more difficulty on standardized linguistic tasks than normally hearing subjects of the same age and gender.