Background Situation-Background-Assessment-Recommendation (SBAR) is a tool for structuring communication between healthcare professionals. SBAR reduces medical errors, however few studies have evaluated its quality in real practice. Aims To describe the quality of SBAR utilization by intensive care unit (ICU) nurses during phone conversations with physicians. To assess the influence of nurses' training, professional experience, and call circumstances on this quality. Study Design This observational study was conducted in the adult ICU of a university hospital in French speaking Switzerland. All consecutive telephone calls from nurses to physicians during a calendar month, were recorded. Those related to a change in patients' clinical status were selected and analysed. The quality of SBAR utilization was assessed using a pre-defined analysis grid. Scores ranged from 0 (worst quality) to 100% (best quality). Nurses' sociodemographics and training record were collected. Multiple regression was used to assess determinants of SBAR quality including nurses characteristics and level of training. Results We analysed 290 phone calls, made by 99 nurses. The median SBAR quality score was 41% (interquartile range [IQR] 33–48). Quality scores varied across the four items of SBAR: Situation 88% (81–94), Background 17% (6–27), Assessment 17% (0–33), and Recommendation 33% (17–40). Factors independently associated with higher SBAR quality were age (−0.66%, p = .002, 95% CI [−1.07; −0.25]), primary language other than French (−8.40%, p = .017, 95% CI [−15.29; −1.51]), lack of ICU expertise (−9.25%, p = .013, 95% CI [−16.5;1–1.99]), and SBAR training in pre-graduate nursing education (+11.53%, p = .028, 95% CI [1.27; 22.79]). Conclusions The quality of SBAR utilization remains low in ICU clinical practice. Pre- and post-graduate training seem to improve its quality. Relevance to Clinical Practice Pre-graduate mandatory training associated with multiple repetitions could improve nurses' SBAR utilization. Training using the SBAR tool should be combined with the development of nursing skills in assessment and clinical judgment.