In the summer 1989 a number of samples were taken in Burley tobacco fields in Campania (south Italy) from plants showing symptoms of mosaic, leaf distortions, and stunting. The disease showed a chess-board spatial pattern, with fields almost totally infected along fields nearly free. In most samples both CMV and PVY were detected, and in all two strains of CMV and three strains of PVY were found. PVY strains showed the same biological and serological behaviour of strains found in the same area in preceding years and already described.. The three strains were differentiated by the reaction on flue-cured tobacco lines resistant and susceptible to the nematode Meloidogyne incognita. CMV strains were differentiated by serological properties and by the response to inoculation of tobacco cultivars, Datura sp., and other hosts. On slab electrophoresis the two strains gave identical RNA patterns. PVY was found only on wild Solanum sp., CMV was found endemic on wild hosts in the field area : on Papaver sp. in spring, on Amaranthus sp. in summer, and on Mercurialis annua in winter. So there is a continuous supply of inoculum, but the field pattern of the disease do not support a major role for the aphids in the spread of the infection on tobacco.