The occurrence of virus diseases on chilli, sweet pepper, tomato, eggplant, pumpkin and cucumber plants in West Malaysia were investigated. More than 80% of the cultivated chilli plants was found to be infected with mosaic disease. And the mosaic disease seemed to cause a severe loss of chilli yields. Out of 9 diseased chilli plants that infected test plants, 3 were found to contain chilli veinal mottle virus (CVMV) alone, while the others were doubly infected with the combination of CVMV and tomato spotted wilt virus (TSWV), CVMV and ordinary strain of cucumber mosaic virus (CMV-O), CVMV and tomato strain of tobacco mosaic virus, and of CVMV and chilli strain of CMV in proportion of 2, 2, 1 and 1. On sweet pepper, the incidence of the virus diseases was slightly less than that of chilli, though both CVMV and TSWV were detected. TSWV was also isolated from tomato and spinach, and produced severe mosaic and malformation of leaves. Zucchini yellow mosaic virus (ZYMV) was isolated from pumpkin and cucumber plants show­ing mosaic symptoms. Cucumber plants infected with ZYMV often produced many deformed fruit. Among the viruses isolated, CMV, CVMV and ZYMV have been reported to be transmitted by aphids in a non-persistent manner. On the other hands, TSWV has been reported to be transmitted by thrips in a persistent manner. Therefore, the protection from these insect vectors is most important for control of these virus diseases.