Background & objective: Patients treated with mechanical ventilation may need sedatives and analgesics due to discomfort, pain, lack of coordination with the device, immunity maintenance, and oxygenation elevation. The use of sedation scoring protocols and systems reduces the duration of mechanical ventilation and hospitalization. Therefore, this study aimed to investigate the effect of controlled sedation based on the Richmond model on the duration of mechanical ventilation in patients admitted to the ICU. Methodology: This experimental study was performed on 60 patients admitted to ICU, who had been selected by simple random sampling and divided in two intervention and control groups. The data collection tools included the Richmond Agitation Sedation Scale (RASS), and Berne separation program checklist. In the intervention group, intervention was performed according to the standard Richmond protocol, but the control group received only the routine care. After the intervention, data were collected at 24 hours, 48 hours and 72 hours after the intervention by SPSS-21 statistical software, and then were analyzed by descriptive statistics (mean, standard deviation) and inferential statistics (paired t-test, independent t-test and repeated measure).