A type of tomato streak due to a single virus, considered to be a strain of the potato virus Y complex, has been recorded from several tomato growing areas in the state of São Paulo. Tomato streak is considered different from a disease described from Piedade and also caused by a strain of potato virus Y. Differences were noted in symptomatology, host range, and virus properties. Tomato streak in São Paulo resembles closely a disease reported from southern Florida. On tobacco the tomato streak strain of the potato Y virus induces wilting of the lower leaves, as it was noticed on tobacco plants infected with veinbanding in Kentucky. A correlation between severe outbreaks of tomato streak and the presence of old sweet pepper plantings in the vicinity of the tomato plantings has been noticed. Potato plantings are not considered a virus source because most varieties are not susceptible to the virus. Tomato streak is easily transmitted mechanically and it is suggested that some field spread might occur as a result from handling the plants in operation such as sucking, tiemg them on the stacks and so on. Aphis rumicis, Myzus persicae, Macrosiphum solanifolii, and Pentatrichopus fragaefolii were able to transmit the virus. Control measures aimed at eliminating virus sources and controlling the vectors are suggested.