Dejan Ljiljak is one of the most experienced Croatian clinical embryologists, with extensive expertise in the treatment and research of human infertility. He is Head of the Department of Clinical Embryology at the Ob/Gyn clinic at University Clinical Hospital Center Sestre milosrdnice in Zagreb.

He is the author of numerous professional and scientific papers, including two chapters in an international textbook, and an invited speaker at international scientific and professional conferences. Dejan Ljiljak has experience as a reviewer for two leading journals in reproductive medicine. At the moment he is president of the Croatian Society of Clinical Embryologists. Also, he is the national representative of Croatia in ESHRE (since 2020) and a representative on the EIM ESHRE board. As a member of ALPHA Scientists in Reproductive Medicine, he follows the activity of the society.

Dejan Ljiljak is an educational mentor to many clinical embryologists. He is a member of expert bodies under the Ministry of Health of Croatia and a consultant and supervisor for multiple reproductive centres in Croatia and worldwide.