Buyin

Buyin may refer to:
 * Buyin, an alternate name of Buin Zahra, a city in Iran
 * Buyin, Zanjan, a village in Zanjan Province, Iran
 * BUYIN, a procurement joint-venture by Deutsche Telekom and Orange
 * "Buy-in", a poker term, see: Glossary of poker terms
 * The purchase of a company by a new manager or management team, see Management buy-in