Bidens pilosa L. is a cosmopolitan annual herb, known for its traditional use in treating various diseases and thus much studied for the biological activity of its extracts, fractions and isolated compounds. Polyacetylenes and flavonoids, typical metabolite classes in the Bidens genus, predominate in the phytochemistry of B. pilosa. These classes of compounds have great taxonomic significance. In the Asteraceae family, the acetylene moiety is widely distributed in the Heliantheae tribe and some representatives, such as 1-phenylhepta-1,3,5-triyne, are noted for their biological activity and strong long-wave UV radiation absorbance. The flavonoids, specifically aurones and chalcones, have been reported as good sub-tribal level markers. Natural products from several other classes have also been isolated from different parts of B. pilosa. This review summarizes the available information on the 198 natural products isolated to date from B. pilosa.