Several rates of the sulfonylurea herbicides, Glean and Oast, were applied to two resistant tobacco mutants in seedbed and field experiments at two locations in North Carolina. The herbicide-resistant tobaccos were developed from cell cultures of Nicotiana tabacum L. cv. Xanthi by researchers at E.I. DuPont de Nemours and Co. In the absence of weeds or herbicides, the mutant types yielded as much green leaf as the wild-type parent, indicating that the controlling genes have no detrimental effect on yield or nicotine production. On the heavier soil type, only the highest rate of Oast caused a stunting of the resistant tobaccos, but the susceptible wild type was severely retarded by all rates of both herbicides. In the lighter, sandier soil, all rates caused a reduction in seedling population in the seedbed test. The field results indicate that, with judicious selection of herbicide type and rate for each soil type and weed spectrum, complete control of all weeds can be achieved with no reduction in plant yield. Weeds controlled by Glean included : lambsquarter, ragweed and horsenettle. Oast controlled these as well as annual grasses, morning glory and yellow nutsedge.