Period Change and Surface Activity of the Eclipsing Binary UV Leonis From Johnson B and V photometric measurements of V=8.98 mag eclipsingbinary UV Leonis we calculated the epochs of primary and secondaryminima, which we used to complement the published O-C catalog by Kreineret al. (2000). From this we give a brief analysis of the observed periodchange and give qualitative presumptions about the physics that mighthave caused such a change. Further on, we use the observed systematicvertical shift in light curves as an indication of the surface activityof UV Leonis.