  We compute a number of universal amplitude ratios in the three-dimensional
Ising universality class. To this end, we perform Monte Carlo simulations of
the improved Blume-Capel model on the simple cubic lattice. For example, we
obtain A_+/A_-=0.536(2) and C_+/C_-=4.713(7), where A_+- and C_+- are the
amplitudes of the specific heat and the magnetic susceptibility, respectively.
The subscripts + and - indicate the high and the low temperature phase,
respectively. We compare our results with those obtained from previous Monte
Carlo simulations, high and low temperature series expansions, field theoretic
methods and experiments.
