ABSTRACT The aim of the article is to present the patronage of the Princess Anna Vasa (1568–1625) in the field of botany and Protestant theology in Poland and to present arguments in favor of the hypothesis about her co-authorship of the polemical brochure Slaktarebenck (1617). Anna’s merit is the significant financial support in publishing Zielnik … (1613) by Simon Syreński (1540–1611). This publication – herbarium vivum – one of the most extensive books published in Poland until the end of the 18th century, is also the largest herbarium in Central and Eastern Europe from the old days. The princess’s natural science interests were expressed, among others, by the patronage of Paul Guldenius (? 1588–? 1658), the future creator of the Polish pharmaceutical nomenclature (1641). Anna’s political significance during the period of Catholic confessionalization in the Polish-Lithuanian Commonwealth is evidenced by the dedication of the postyll (1620–1621) by Samuel Dambrowski (1577–1625), the most popular collection of Polish Lutheran sermons until the mid-twentieth century. Her role as the Protestant protector was also appreciated on the European forum by Daniel Cramer (1568–1637), who dedicated his edition of Luther’s Bible to her.