Abstract: A simple and rapid method for large scale preparation of 5S RNA from plant leaves is described. To begin, all nucleic acids were extracted from the leaves with a mixture of phenol-chloroform-n-butyl alcohol and extracting buffer. After precipitation of the high-molecular-weight nucleic acids from the crude extract with 2 M LiCl, the low, molecular-weight RNA in the supernatant (containing about 6% 5S RNA) could be separated by eleetrophoresis on denatured polyaerylamide gels. The band of 5S RNA was excised from the preparatory slab gel under UV light and then purified by eleetrophoretie elution. In our experiments, several mg pure 5S RNA was obtained from 100 g leaves in a single run which takes about 4 days. The purified final produet was pure as showing a single hand on denatured polyaerylamide gel and a typical UV absorption peak of nucleic acid. The sedimentation coefficient (S20w) of the product was 4.6 as determined by ultracentrifugation.