Radar observations of 433 Eros were made at the Arecibo Observatory using a wavelength of 70 cm during the close approach of Eros to Earth in mid-January, 1975. A peak radar cross section of 39 ± 15 km 2 was observed. The spectral broadening obtained was approximately 30 Hz, which is consistent with a value of 16 km for the maximum radius of the asteroid. The surface of Eros appears to be relatively rough at the scale of a wavelength as compared to the surfaces of the terrestrial planets and the Moon. The composition of the surface is not well determined, except that it cannot be a highly conducting metal. A single measurement each of round-trip echo times delay and doppler shift was made.