ENThe present scientific review supplements the latest biography of Hieronim Florian Radziwiłł (1715– 1760). Its author, Paweł Gad, convincingly refutes the thesis that the Lithuanian aristocrat was a fool and a sadist, as previously argued by many historians. He shows that Radziwiłł’s behaviour, although peculiar, fitted into the acceptable standard of the Polish-Lithuanian magnates of the eighteenth century. The biography focuses on Hieronim’s family life, political activity, passions, and cultural interests while downplaying other issues, such as his economic activity, religiosity, and relationship with various confessions. Based on manuscript sources unknown to Paweł Gad, the reviewer confirms and broadens the aristocrat’s picture that emerges from his biography. The weakness of the reviewed book is the omission of various publications and careless editing. Keywords: Hieronim Florian Radziwiłł, Radziwiłł family, Grand Duchy of Lithuania, 18th century, biographies.