ABSTRACT: Herbal teas have been consumed worldwide for a long history. The health-promoting benefits of herbal teas have been widely recognized, such as antioxidant, antidiabetic, anti-carcinogenic, and antimicrobial activities. However, multiple harmful substances have been detected in herbal teas, such as pesticide residues, polycyclic aromatic hydrocarbons, pyrrolizidine alkaloids, heavy metals, and radionuclides. The presence of these harmful substances could cause potential health risks to human beings, including some acute toxic syndromes and chronic diseases, such as cancer, kidney stones, tooth wear, and allergy. This review summarized the current knowledge about determination and evaluation of harmful substances in herbal teas.