Justus Liebig University Giessen (JLU) is a public research university located in Giessen, in the German state of Hesse. Chartered on 19 May 1607, it ranks among the oldest institutions of higher education in Germany. Originally founded as a Lutheran academy, it has since developed into a comprehensive research university. The institution takes its name from the chemist Justus von Liebig, credited with pioneering modern agricultural chemistry and the development of artificial fertiliser, whose nineteenth-century work at the university significantly advanced the natural sciences.

The university offers programmes across a broad spectrum of disciplines, including the humanities and arts, law, economics and business, the social sciences, the natural sciences, medicine, dentistry and veterinary medicine. Veterinary medicine and the agricultural sciences are among the fields for which Giessen has long been recognised. Teaching and research are organised across a number of faculties, and the institution maintains close academic and clinical ties with the neighbouring University of Marburg in the surrounding region of central Hesse.

With an enrolment of roughly 24,961 students and a workforce of about 5,853 staff, Justus Liebig University is one of the larger universities in Hesse, drawing students from across Germany and abroad. In EduRank's 2026 assessment it is placed around 28th nationally among German universities and 331st worldwide, reflecting its research output and academic reputation. The university continues to combine its historic heritage with a wide-ranging teaching and research mission that spans the sciences, humanities and professional disciplines.