The influence of lunar phases on the activity of phlebotomine sand flies was evaluated in Vicosa, Minas Gerais, Brazil. The insects were collected by illuminated Shannon traps and Falcao light traps, between 1830 and 2230 h on 44 nights, divided between the dry and rainy seasons, and among each of the 4 lunar phases. A total of 888 sand flies was collected, belonging to 10 Lutzomyia species. The dominant species in both seasons of the year and in all lunar phases was Lutzomyia intermedia. A significant difference was found in the abundance of L. whitmani among lunar phases. No significant difference was found in frequency of sand flies collected among lunar phases. Females of L. intermedia initiated activity earlier during the crescent and full moon phases than during three-quarter and new phases. Based on the premise that sand flies would exhibit normal phototaxis in the absence of moonlight, activity should be unaffected under a new moon, whereas light reflected by the moon in its brightest phases (crescent and full) should shift the period of activity of the sand flies so that it does not coincide with the period in which the moon is visible, or should reduce attractiveness of light traps to the insects by providing less background contrast.