 His scientific and research activity focuses mainly on neuroimmunoendocrinology - an interdisciplinary field of research, dealing with connections between the nervous, immune and endocrine systems.That includes research on the effect of cytokines on the activity of the hypothalamic-pituitary system, pathogenesis and diagnostics of immune-related endocrinopathies and the role of neoangiogenesis in the development of endocrine glands.Professor Stepien has also significantly contributed to the organization of science and the development of higher medical education in Poland - he led the transformation of the Medical Academy of Lodz into the Medical University of Lodz in 2002.