A 41-year-old man with prolidase deficiency has had chronic leg ulcers and recurrent cellulitis for most of his life. Until recently he had been hospitalized at least annually for this and suffered significant morbidity as a result. Since commencing topical 5% proline in white soft paraffin ointment to treat the leg ulcers, there has been marked improvement in the ulcers and decreased frequency of hospitalizations for cellulitis. This lends further support to the use of topical proline in the treatment of patients with skin ulcers secondary to prolidase deficiency.