Prior to the start of this project, several recombinants had been selected from a library of human genomic DNA cloned in lambdaCharon 4A using a mixed tRNA probe (Goddard et al., 1983). One such clone was termed lambdaHt363. Restriction digests of DNA from this recombinant were transferred to nitrocellulose membranes and hybridised to the mixed tRNA probe used in the original cloning. Several fragments from each digest hybridised to the probe, indicating the possible presence of a tRNA gene cluster. The cluster was partially characterised (McLaren and Goddard, 1986) and found to contain a 4.2 kb Bam HI fragment carrying three tRNA genes, coding for tRNA Lys, tRNA Gln and tRNA Leu. The partial sequence of a fourth gene, coding for tRNA Gly, was found at one end of an 800 bp Eco RI fragment, thought to originate from close to the right hand arm of the lambda recombinant.