  We performed photometry with a 1 minute time resolution of the symbiotic
stars EF Aquilae, AG Pegasi and SU Lyncis in Johnson B and V band. Our
observations of the symbiotic Mira-type star EF Aql demonstrate the presence of
stochastic light variations with an amplitude of about 0.25 magnitudes on a
time scale of 5 minutes. The observations prove the white dwarf nature of the
hot component in the binary system. It is the 11th symbiotic star (among more
than 200 symbiotic stars known in our Galaxy) which displays optical
flickering. For SU Lyn we do not detect flickering with an amplitude above 0.03
mag in B band. For AG Peg, the amplitude of variability in B and V band is
smaller than 0.05 mag and 0.04 mag respectively.
