Relative enophthalmos is often cited as a causative factor in the development of involutional entropion. However, the association between enophthalmos and involutional entropion is largely anecdotal; no patient population study has been performed to determine if a causal relationship exists. This prospective clinical study compares exophthalmometric values in a population of patients with involutional entropion to an age- and sex-matched control group. Hertel exophthalmometric measurements were obtained on 56 patients with involutional entropion presenting over a 2-year period. Exophthalmometric measurements were also obtained in a group of 53 age- and sex-matched control patients presenting for evaluation and management of unrelated periocular disorders. Fifty-three patients presented with unilateral entropion and three patients presented with bilateral lower lid entropion. The mean of exophthalmometric measurements was within 16.0 mm in the entropion group and 16.15 mm in the control group. Eyes with involutional entropion are no more likely to have enophthalmos than is the uninvolved contralateral eye or normal eyes of an age- and sex-matched control population. Enophthalmos does not appear to play a role in the development of involutional entropion.