Kurt Polycarp Joachim Sprengel (3 August 1766 – 15 March 1833) was a German botanist and physician.
Sprengel was born at Boldekow in Pomerania.
His uncle, Christian Konrad Sprengel (1750-1816), is remembered for his studies in the fertilization of flowers by insects - a subject in which he reached conclusions many years ahead of his time. His father, a clergyman, provided him with a thorough education of wide scope; and the boy at an early age distinguished himself as a linguist, not only in Latin and Greek, but also in Arabic. He appeared as an author at the age of fourteen, publishing a small work called Anleitung zur Botanik für Frauenzimmer ("guide to botany for women") in 1780.
In 1784 he began to study theology and medicine at the university of Halle, but soon relinquished the former. He graduated in medicine in 1787. In 1789 he was appointed extraordinary professor of medicine in his alma mater, and in 1795 was promoted to be ordinary professor. He devoted much of his time to medical work and to investigations into the history of medicine; and he held a foremost rank as an original investigator both in medicine and botany. Among the more important of his many services to the latter science was the part he took in awakening and stimulating microscopic investigation into the anatomy of the tissues of the higher plants, though defective microscopic appliances rendered the conclusions arrived at by himself untrustworthy. He also made many improvements in the details of both the Linnaean and the natural systems of classification.