Ovarian hyperstimulation syndrome refers to complications associated with the use of hormonal agents in assisted reproduction. This syndrome can cause pain in or enlargement of the abdomen, abdominal pressure, enlargement of the ovaries, ovarian cysts and, in its more severe form, the accumulation of fluid in the abdominal cavity. The symptoms of OHSS resolve themselves will sooner or later, but any treatment must always include regular and careful monitoring of the entire stimulation process. With a properly set stimulation protocol, the risk of OHSS is minimal.