Spectra and attenuation profiles of neutrons and gamma rays transmitted through graphite piles were measured by an organic scintillator with an n-γ discrimination technique. The neutrons and gamma rays were produced in a graphite target placed in front of the piles, which were bombarded by 52-MeV protons. The piles were 54 cm high, 90 cm wide, and 11.7, 23.5, and 44.9 cm thick. The energy spectra of neutrons and gamma rays were obtained after unfolding by the FERDO code, from pulse-height distributions. Spectra calculated by use of a Monte Carlo neutron transport code developed for neutrons of energy up to 50 MeV show good agreement with the measured spectra.