AbstractThe feasibility of operating a multistage continuous culture of plant cells was demonstrated forNicotiana tabacum. Cells in the second stage of a two‐stage chemostat were morphologically distinct from cells in the first stage or cells in a single‐stage unit with a holding time equal to the combined holding times in the two‐stage system. Cells in the second stage produced much higher levels of phenolics per unit weight of cells than cells in either the first‐stage or single‐stage unit. The steady‐state was reproduced. When a glucose side stream was fed to the second stage, an increase in apparent cell division was observed with a simultaneous decrease in phenolics productivity. When the toxic precursor phenylalanine was pulsed into the reactor, the quantity of biomass decreased temporarily while phenolic productivity increased. These experiments demonstrate that multistage continuous culture may be useful in increasing secondary metabolite formation in cells and in exploring mechanisms controlling secondary metabolit