Objectives: Intensive care units (ICUs) are characterised by high care complexity and nursing workload, which directly affects patient safety and staff sustainability. Latvia faces a chronic shortage of nurses, particularly in intensive care, yet systematic national data on nursing workload have been lacking. This study aimed to quantitatively assess nursing workload in Latvian ICUs using the Nursing Activities Score (NAS) and to evaluate its relationship with staffing adequacy. Methods: A prospective, multicentre observational study was conducted over six months (May–November 2025) in 14 Lat-vian ICUs representing all three levels of intensive care. Nursing workload was meas-ured using the NAS during each 12-hour shift. A total of 28,079 complete NAS obser-vations were analysed using descriptive statistics, inferential tests (t-tests, ANOVA), mixed-effects modelling, regression analysis, and time-series forecasting. Results: The mean NAS was 65.45 (SD = 25.76), equivalent to an average of 15.71 nursing care hours per patient per day. Workload remained similarly high during day and night shifts. Significant differences were observed between ICUs and care levels, with level 2 units showing the highest workload. The average nursing shortage rate was 42.6% and was strongly predicted by NAS values (R² = 0.115), whereas shift type and unit level had minimal explanatory power. Conclusions: ICU nursing workload in Latvia is persis-tently high and unevenly distributed across units. Staffing levels are not adequately adjusted to actual care demands. Integrating NAS-based workload monitoring into staffing models is essential for evidence-based workforce planning, improving patient safety, and reducing nurse overburdening.