The purpose of this study was to calculate nurse/patient radio by using TISS-28, and to assess time allocation to nursing activities in the intensive care unit. In this study the TISS scores of 416 patients were calculated in the intensive care unit 10 weeks long using the TISS-28 form. In order to determine the duration of the nursing care activities due to nursing care categories the work sampling method was used. A sampling matrix for 10 weeks was created and the nursing care activities were observed 7 days a week for two day shifts (08.00-16.00). The data collection instruments were, the 'TISS-28' and 'Work sampling form for intensive care unit nursing activities'. The TISS-28 point for ICU was 40.41 for day shift. One TISS-28 point equals 11.88 min of the 480 min in each shift. Related literature shows that nursing care activity for one day makes 40-50 TISS score. The percentage of nursing time spent on nursing activities in the ICU was calculated by using work sampling. Results indicated that 44.25 % of nurses time was spent in activities in TISS-28; 12.87% in activities not in TISS-28; 25.8% in indirect patient care, 6.21% in organizational activites,10.64% in personnel activities and 0.15% in other activities. It is shown that category one represents TISS-28 and that the increase in TISS score results in the increase in nursing care activity duration. These result show that the TISS-28 can be useful to determine the patient/nurse ratio in intensive care units.