In March 2019, in Botucatu municipality (Sao Paulo State, Brazil), two unknown cultivars of coleus (Plectranthus scutellarioides), from a flower shop and a private garden, were found showing symptoms of irregular chlorotic and necrotic leaf lesions, with abundant gray sporulation on the abaxial leaf surface. Based on morphological characteristics, molecular data (sequence analysis of the rDNA internal transcribed spacer region and mtDNA regions) and pathogenicity test, the causal agent was identified as P. belbahrii. This is thought to be the first report of P. belbahrii infecting coleus in Brazil. This pathogen is considered a major threat to coleus, being distributed in Japan, the United States, the United Kingdom, and Germany. The occurrence of a similar species in sweet basil in Argentina was also reported, but no downy mildew infection in coleus was published yet in South America.