Spontaneous fission of Cm242 has been investigated by radiochemical determination of the yields of 21 fission products ranging in mass number from 91 to 140. Fission is observed to be asymmetric. The yieldmass curve exhibits somewhat narrower peaks than observed in induced fission and a peak-to-trough ratio of greater than 700 to 1. Prominent fine structure is observed in the mass distribution, and an analysis of this phenomenon is made. The distribution of nuclear charge in spontaneous fission appears to be essentially the same as that in low-energy induced fission.