Degree in NL-EN-IT translation from the University of Amsterdam (1982). One year in London to study at the Laban Centre of Movement and Dance. Subsequently employed by the European School of Oncology at the National Cancer Institute in Milan, Italy, as organizer of postraduate courses for oncologists and technical editor of the ESO monograph series. Freelance translator since 1988. Copy editor of three English-language medical journals from 1992 to 2017 (specialties: oncology, nephrology, nutritional therapy, biomarkers). Currently working mostly as authors' editor in biomedicine. Member of AITI (Associazione Italiana di Traduttori e Interpreti), MET, and EASE (European Association of Science Editors).

Marije de Jager: Journal copy-editing in a non-anglophone environment. Chapter 10 in Supporting Research Writing. Roles and challenges in multilingual settings. Valerie Matarese, Ed. Chandos Publishing, Cambridge, UK, 2012.
Marije de Jager: Striking a blow for originality. A note from the copy editor. Tumori 2012; 1: i-ii.
Mary Ellen Kerans and Marije de Jager: Handling plagiarism at the manuscript editor's desk. European Science Editing, August 2010; 36: 62-66.
Marije de Jager: METM09: Translation, editing, writing: broadening the scope and setting limits. European Science Editing, February 2010; 36: 15-16.
Marije de Jager: Communication support across the disciplines - METM 2008. European Science Editing, February 2009; 35: 15.
Marije de Jager: Building bridges, constructing networks: METM 2007. European Science Editing, February 2008; 34: 17-18