Contrary to the well-documented incidence and severity of Citrus variegated chlorosis (CVC) throughout the sweet orange groves of Sao Paulo state (Brazil), the incidence and distribution of its causal agent, Xylella fastidiosa, is not well known. Sweet orange samples selected according to variety and age were collected from commercial groves in northern, central and southern regions of Sao Paulo state and analysed visually for the presence of symptoms and by PCR for the presence of X. fastidiosa. A decreasing gradient of both infected and symptomatic trees from northern to southern regions of the state was observed. However, there was a higher incidence of latent infection (symptomless trees) in the southern (32%) than in the northern and central regions (16%). The survey disclosed an increasing gradient of CVC and X. fastidiosa incidence according to the age of the trees. Infected trees younger than two years were observed only in the central region. CVC symptom expression is related to environmental conditions and the incidence of symptomatic trees does not correspond with that of trees infected by X. fastidiosa.