Although orthorexia nervosa, the fixation on health-conscious eating behaviour, was first described in the 90 s, there is no clear understanding whether existing ON measures are appropriate for its assessment. The objectives of the present study were to: (1) examine the psychometric properties of the Polish version of the DOS (PL-DOS) and to compare the PL-DOS with the English version of the DOS (E-DOS) as well as (2) evaluate the prevalence of ON among Polish university students and compare the prevalence rates of ON among Polish and U.S. students.