We present some results of our initial optical observations of the El Chichon volcanic cloud. These observations were made at the Geophysical Monitoring for Climatic Change Mauna Loa Observatory, Hawaii, and consist of lidar profiles, optical thickness, spectral variation in optical thickness and changes in global and direct solar broadband fluxes. Particle size distribution and cloud mass information contained in the optical thickness observations are discussed. It is clear that the atmospheric radiative effects of the El Chichon cloud far exceed the effects of all other volcanic clouds observed at Mauna Loa since observations were begun in 1958.