Material and Methods. A cross-sectional design study was conducted in three intensive care units of Lithuanian hospitals from March to December 2019. Totally, 228 intensive care unit nurses working in intensive care units participated in the study (response rate was 90.8%). The Multidimensional Fatigue Inventory was employed to assess nurse’s fatigue. The study protocol was approved by the Bioethics Centre of Lithuanian University of Health Sciences (No. BEC–SL(M)–196).

Results. Nurses assessed general fatigue with the highest scores (41.06 ± 22.82), and the lowest scores indicated reduced activity (26.81 ± 18.23). General fatigue was not associated with the nurses’ age and working shift. Physical fatigue was more prevalent among nurses working in 24-h shifts compared with daytime shifts with the scores of 41.20 ± 21.86 and 35.82 ± 25.77, respectively.

Reduced motivation (31.09 ± 17.86) and mental fatigue (31.70 ± 24.81) were higher in nurses working in the daytime shift than in the 24-h shift. General fatigue correlated significantly positively with physical fatigue (r = 0.774, P < 0.001), mental fatigue (r = 0.548, P < 0.001), reduced activity (r = 0.614, P < 0.001), and reduced motivation (r = 0.607, P < 0.001).

Conclusions. General fatigue was most frequent among intensive care unit nurses. Daytime shift was associated with reduced nurses’ activity; furthermore, younger nurses indicated higher mental fatigue.