Uptake by plant protoplasts isolated from cultured cells was demonstrated using Escherichia coli14C-DNA and Ammi visnaga protoplasts. About 0.6 to 2.8% of exogenous E. coli14C-DNA was taken up into the protoplasts, of which about 20% appeared to be acid-precipitable. The time course of uptake, the effect of incubation temperature, and the effects of DNA and protoplast concentration were studied. DEAE-dextran, poly-L-lysine, and poly-L-ornithine were found to enhance the uptake markedly.