The ground and the two lowest-lying excited states of pyrene were studied using pi-CASSCF and pi-MRSD-CI calculations. The results show that the multireference effect is crucial in predicting the correct order of the two lowest-lying singlet excited states, the 1(1)B(2u)(S-1) and the 1(1)B(3u)(S-2) states. The calculated excitation energies from So to SI and from S-0 to S-2 are 3.97 and 4.60 eV, respectively, which are about 120% of the experimental values. Various levels of the calculations are presented to analyze the electron correlation effects.