Keratitis-ichthyosis-deafness syndrome is a rare genodermatosis, which has recently been connected with mutations in the connexin-26 gene, GJB2. We present a 15-year-old boy with erythroderma, hyperkeratotic plaques and deafness. Sequencing analysis showed a heterozygous missense mutation D50N (148G>A) in GJB2. The boy has not yet manifested characteristic eye lesions but his case shows that tardy development of eye signs should not preclude a clinical diagnosis of keratitis-ichthyosis-deafness syndrome. Besides the typical clinical features, the patient's height was above the 98th percentile and he displayed a delayed bone age in his hands. Additionally, he suffered from migrainoid headaches and the results of a magnetic resonance scan of the cerebrum showed he had a large cisterna magna which probably occurred independently from the syndrome. This patient is the first Danish patient in whom the keratitis-ichthyosis-deafness syndrome has been verified by mutation analysis.