  We present first results on polarization swings in optical emission of
blazars obtained by RoboPol, a monitoring program of an unbiased sample of
gamma-ray bright blazars specially designed for effective detection of such
events. A possible connection of polarization swing events with periods of high
activity in gamma rays is investigated using the dataset obtained during the
first season of operation. It was found that the brightest gamma-ray flares
tend to be located closer in time to rotation events, which may be an
indication of two separate mechanisms responsible for the rotations. Blazars
with detected rotations have significantly larger amplitude and faster
variations of polarization angle in optical than blazars without rotations. Our
simulations show that the full set of observed rotations is not a likely
outcome (probability $\le 1.5 \times 10^{-2}$) of a random walk of the
polarization vector simulated by a multicell model. Furthermore, it is highly
unlikely ($\sim 5 \times 10^{-5}$) that none of our rotations is physically
connected with an increase in gamma-ray activity.
