This study investigated whether the review of systems (ROS), an evaluation method that covers all organ systems, improves the quality of pharmaceutical care provided in intensive care units (ICUs). We retrospectively examined patients from the respiratory and emergency intensive care departments admitted to the ICU of our hospital in 2012 (before the introduction of ROS; non-ROS group, n = 93) and in 2014 (after the introduction of ROS; ROS group, n = 65). The number of pharmaceutical interventions and adverse drug events prevented by pharmacists per 1000 patient days were higher in the ROS group (265.7 and 57.8 for the ROS group and 190.8 and 39.9 for the non-ROS group). Pharmacists' proposals were accepted at a significantly higher rate in the ROS group than in the non-ROS group (89.5% vs 72.3%, P < 0.01), and the accepted proposals in the ROS group were implemented for a wider range of organ systems. These results indicate that the ROS was helpful in terms of identifying the patients' clinical manifestations and evaluating the adequacy and safety of medication administered in the ICU, which resulted in improved and precise proposals by pharmacists. Moreover, the ROS approach introduced in this study was considered to be suitable for pharmaceutical activities in the ICU and to contribute to improving the quality of pharmaceutical care.