Summary.A comparison was made between diphenamid and napropamide with regard to phytotoxicity to pepper and weeds under glasshouse and field conditions. Diphenamid was considerably less phytotoxic than napropamide in inhibiting root elongation and shoot growth of pepper seedlings. Plant growth was reduced when the roots were exposed to either one of the herbicides, but growth of the shoot through treated soil was not adversely affected. Since diphenamid was found to be more leachable into soil, it might become more available to the roots and damage the crop plants. Graminaceous weeds were very sensitive to both herbicides, whereas several dicotyledonous weeds were more susceptible to napropamide. Selectivity of both herbicides at a late pre‐emergence application to direct‐seeded pepper was found satisfactory in two field experiments on different soil types.Action sélective de la diphénamide et de la napropamide sur le piment et les mauvaises