Objective: To determine the relationship between the demands of the nursing workload and the severity of the patient’s condition in adult intensive care units in the city of Cartagena during July 2008. Methodo: This is a longitudinal study with a sample comprised of 42 patients. TISS-28 (Therapeutic Intervention Scoring System) and Apache II (Acute Physiology and Chronic Health Evaluation) records were obtained. Arithmetic average, standard deviation and proportions were calculated, as was the Pearson correlation coefficient. Results: In this study involving a total of 42 patients, the average age was 58.2 years (IC 95% 52.1-64.4), and 51.3 percent of the patients in the sample were women. Forty-two (42) Apache II evaluations were obtained when the patients were admitted to the ICU, with an average of 28.9, and 66.7 percent if the patients (28) have a poor prognosis. There were 188 TISS-28 scores, with an average of 28.7 (IC 95% 25.7 - 31.7) per patient. The average TISS upon release from the ICU was 25.7 (95% CI 22.4 to 28.9) per patient. In all, 61.9 per cent of the patients were Class III. The nurse/ Class IV patient ratio was 0.57 less than 1:1. The study found a relationship of 0.55 between Apache II and TISS-28. (0.501-0.75) and a coefficient of determination equal to 0.38 (p<0.05). Conclusions: There is a moderate correlation between TISS-28 and Apache II that shows an overload of nursing work in intensive care units. This has repercussions on the direct care provided to critical patients.