One of the highly important cares in intensive care units (ICUs) for keeping the airway and improving ventilation and oxygenation is suctioning. This must be done in a way so that, it can have the fewest effects or complications for the patient, in addition to the mentioned advantages. The goal of the present study is comparison of the two standard and routine suctioning methods on vital signs and arterial blood oxygen saturation and sedation level of the patients hospitalized in ICUs. The present quasi-experimental study was conducted in 2012 on 80 patients under mechanical ventilation hospitalized in ICUs of Zahedan City. The patients were selected purposively and were randomly divided into two groups. In the first group, suctioning was done with the standard method recommended by American Association for Respiratory Care (AARC) and in the second group, it was conducted based on routine nursing cares. The data was collected by means of Richmond scale and bedside patient monitoring, before and in the minutes 1, 5, 10, 15 after suctioning. The results showed that suctioning, in the routine method used, leads to more agitation among the patients and this agitation continued until the minute 10 after suctioning and there was a statistically significant difference between the two groups in minutes 1 and 5 (p=0.000, p=0.000). The vital signs in both groups had increased after suctioning and these changes were more in the second group but in most of the times there was no significant difference between the two groups. Also, the level of arterial blood oxygen saturation after suctioning had increased in both groups but in group 1 these changes were more and in the minutes 5, 10, 15 after suctioning there was a higher significant difference than before suctioning (p=0.001 ،p=0.000 ،p=0.000); yet in the second group no significant difference was observed in any one of the times (p>0.05). The results of the present study showed that suctioning in the standard method brings about less agitation for the patients. It brings about fewer changes in vital signs and also leads to the increase of arterial blood oxygen saturation. Thus, it should be contained in the work program of the nurses with adequate training.