Introduction <p>Depictions of the iliolumbar ligament in modern scientific publications and medical textbooks may vary noticeably and sometimes even contradict one another. The authors working on the subject seem to agree only on its general location and vague descriptions of function. However, their opinions appear to differ in every other aspect. Most extreme seems to be the disparity of opinions regarding anatomy of the development of the ligament, some authors claim that during its prenatal development and first few decades of life iliolumbar ligament is in fact a muscular structure, whereas other authors seem to negate this theory.</p> Purpose <p>This study aims to examine the ligaments presence in human foetuses and verify the premise regarding its muscular character.</p> Methods <p>16 foetuses with mean age 18.1 weeks were examined. The samples were extracted from the specimen belonging to the collection of Department of Descriptive and Clinical Anatomy of Medical University of Warsaw. The materials were prepared by hand with surgical and microsurgical tools with use of operating microscope. Additionally histological examination was performed on the foetal tissues.</p> Results <p>During the examination strands and bands of collagenous tissue were observed in the typical location of the iliolumbar ligament in majority of cases, which suggests presence and development of ligamental structures in foetuses as early as in 15th week of development.</p> Conclusion <p>The iliolumbar ligament is typically present and recognizable during the prenatal development, thus it cannot be stated that it comes to be later in life due to metaplasia.</p>