A method is proposed for recovering oil by retorting oil shale shattered by deep underground nuclear explosions. Because most of the oil will be obtained from chunks of oil shale with maximum dimensions exceeding 1 ft, retorting times of up to several weeks are needed for complete recovery. A study of the heat economy of the retorting process in an underground nuclear chimney suggests that the nuclear detonation itself and the subsequent controlled combustion of residual carbon in retorted oil shale will provide ample energy. The proposed method is shown to be thermally efficient. A 5-ft diam., 12-ft high aboveground batch retort has been constructed for the experimental retorting of mixtures of oil shale particle sizes. Low rates of air and recycle gas, low-retorting temperatures and slow combustion front advance have characterized its operation. In spite of imperfect mist-separating equipment, recoveries of about 60% of Fischer assay have been obtained. The particle size distribution of 30 gal/ton oil shale has not been appreciably altered by the retorting. The proposed technique appears to be a promising one for recovering the oil from thick, deep, oil shale deposits. (22 refs.)