  Using a sample of 454 mira light curves from the ASAS survey we study the
shape of the light variations in this kind of variable stars. Opposite to
earlier studies, we choose a general approach to identify any deviation from a
sinusoidal light change. We find that about 30% of the studied light curves
show a significant deviation from the sinusoidal reference shape. Among these
stars two characteristic light curve shapes of comparable frequency could be
identified. Some hint for a connection between atmospheric chemistry and light
curve shape was found, but beside that no or only very weak relations between
light curve shape and other stellar parameters seem to exist.
