The DNA sequences of the BamHI b fragment and of a Smal-BamHI subfragment of BamHI e from the herpes simplex virus type 1 (HSV-1) genome have been determined. These restriction fragments are located at each end of the UL sequence and span the RL/UL junctions. The BamHI b fragment contains over 6 kb of the Rl element. The DNA sequence of the two restriction fragments was determined by chain terminator sequencing reactions of recombinant M13 clones generated from sonicated DNA or restriction enzyme digested DNA.