ABSTRACT Objectives: to analyze the predictors of moral harassment in nursing work in critical care units. Methods: a cross-sectional study conducted in a public hospital in Fortaleza, Ceará, with 167 nursing professionals in 2016. Sociodemographic/occupational questionnaire and Negative Acts Questionnaire Revised were applied. The analysis included descriptive statistics, measures of central tendency and dispersion, as well as Mann-Whitney, Kruskal-Wallis and Conover Inman U-tests for multiple comparisons. Results: there was a 33% prevalence of self-perception of moral harassment, highlighting personal/professional disqualification and work-related harassment. The predictors of moral harassment included age, time working in the job and time in the unit, employment relationship and sector. Conclusions: young professionals (< 30 years), cooperative, crowded in intensive care or emergency units, with less time working in the job (< 5 years) or greater time in the unit (above 10 years) are the biggest victims of moral harassment in the work of nursing in critical environments.