We present results of period analysis of ASAS, MACHO and OGLE light curves of 79 symbiotic stars classified as S and D-type. The light curves of 58 objects show variations with the orbital period. In case of 34 objects, orbital periods are estimated
for the first time, what increases the number of symbiotic stars with known orbital periods by about 64 %. The light curves of 46 objects show, in addition to the long-term or/and orbital variations, short-term variations with time scales of 50-200 days most likely due to stellar pulsations of the cool giant component. We also report eclipse-like minima and outbursts present in many of the light curves.
