Group sex is sexual behaviour involving more than two participants at the same time. The main focus of this page is group sex among humans

Any and all sexual behaviour performed by two people can be a part of group sex as well as a number of behaviors only possible with more than two people. Group sex involving one participant being penetrated by multiple people is sometimes termed a gang bang.

Group sex can occur amongst people of all sexual orientations and genders.

Group sex may involve three or more people of any gender or sexual orientation. The events themselves may be characterized by sex for example a straight group sex session would involve only heterosexual sex. Some venues for group sex may be intended for a particular group or groups of people. Different types of group sex may or may not involve switching partners. Some sex clubs for example require entrants to come in pairs and do not typically involve actual physical contact between people in different pairs. Group sex may involve a specific set of sexual activities for example some involve BDSM while "vanilla" group sex does not.

Bukkake is a group sex practice where multiple men ejaculate on a male or female subject. At the end of the process the subject may drink the semen. Its first filming is credited to adult filmmaker Kazuhiko Matsumoto in 1998. Bukkake originally became a porn trend because of the mandatory porn mosaic in Japan. Since the directors could not show penetration they had to figure out new visually appealing ways to approach sex acts that would satisfy the audience without violating Japanese law. Some women have gone public regarding their sexual enjoyment of bukkake one prominent example is Catherine Millet.