Topical application of the endekapeptide eledoisin has been reported to increase tear secretion in patients with dry eye. However, to date the efficacy of eledoisin has been proved only by methods that are not easily reproduced and have an enormous intraindividual scatter range (Schirmer test, basic secretion test). In the present study the effect of topically applied eledoisin on tear volume and tear flow was determined quantitatively by means of objective fluorophotometry in 40 subjects, 20 of whom suffered from severe dry eyes. Both tear volume and tear flow were found to be significantly increased up to 2 h after instillation, reaching a maximum 1 h after application (tear volume: +87% and +35% for dry eyes and healthy controls, respectively; tear flow: +250% and +27% for dry eyes and healthy controls, respectively).