Citrus is one of the genus of the Rutaceae family originating from Asia. This study aims to determine the histochemical characteristics of the fruit skin of four species of Citrus (Rutaceae) from Pekanbaru Riau and the level of toxicity based on the LC50 value. The samples used were Citrus aurantiifolia, Citrus hystrix, Citrus limon, Citrus medica. This research was conducted from October 2024 …