  We discuss the equation of state for QCD at non-zero temperature and density.
We present results of a simulation for QCD with 2 flavors of p4-improved
staggered fermions. Derivatives of $\ln {\cal Z}$ with respect to quark
chemical potential $\mu_q$ up to fourth order are calculated, enabling
estimates of the pressure, quark number density and associated susceptibilities
as functions of $\mu_q$ via a Taylor series expansion. We also discuss the
radius of convergence of the expansion as a function of temperature. It is
found that the fluctuations in the quark number density increase in the
vicinity of the phase transition temperature and the susceptibilities start to
develop a pronounced peak as $\mu_q$ is increased. This suggests the presence
of a critical endpoint in the $(T, \mu_q)$ plane.
