DNA copies of rabbit globin mRNA have been inserted into the plasmid mini-ColEl. After addition of poly(dT) tails, the plasmid was used to prime the copying of mRNA by reverse transcriptase. Mini-ColEl carrying globin sequences were denatured and annealed with mini-ColEl tailed with poly(dA). Functional plasmids containing the synthesised globin sequences were isolated by transfection in E. coli.