Ototoxicity of cis-platinum and its relationship to eye colour. The following hypothesis is presented: that the susceptibility of an individual patient to hearing loss as a result of cis-platinum administration can be predicted on the basis of eye colour. The rationale is that the melanin content of the inner ears is related to that of the eyes; dark eyes contain more melanin than light-coloured eyes; and melanin causes the accumulation of the ototoxic drug within the inner ear. Hence those with dark eyes will suffer greater damage to the hearing than those with pale eyes. An investigation that confirmed this hypothesis is reported. In addition to cochlear damage there is a significant likelihood of damage to the auditory nerve as a result of the treatment. 