The purpose of the study was to evaluate painful procedures in ICU patients and to investigate their effect as well as the role of analgesia in the outcome. We measured pain level and vital signs before, during and after potentially painful procedures by using the Behavioral Pain Scale (BPS) and the Critical Care Pain Observation Tool (CPOT). We analyzed the correlation of these measurements and of analgesia with the outcome. Twenty-eight patients were subjected to 160 stimuli. There were statistically significant differences in pain scores and most vital signs between the different timepoints (before-during, during-after). Most of them were significantly correlated with each other. Physiotherapy proved to be the most painful procedure. Regarding the outcome, the administration of extra analgesia predicted less days of mechanical ventilation ( = 0.015) and of ICU stay ( = 0.016). The higher change in BPS was correlated with more days of mechanical ventilation [B (95% CI) = 3.640 (1.001-6.280),  = 0.007] and of ICU stay [B (95% CI) = 3.645 (1.035-6.254),  = 0.006]. The higher change in CPOT and the nonuse of extra analgesia were related to increased mortality [OR (95% CI) = 1.492 (1.107-2.011),  = 0.009 and OR (95% CI) = 2.626 (1.013-6.806),  = 0.047]. Increased pain in ICU patients was successfully assessed by the BPS and CPOT and correlated to worse outcomes, which the administration of extra analgesia might improve.