ObjectiveTo compare first attempt success rate for ultrasound-guided (USG) versus direct palpation (DP) for radial, femoral, and dorsalis pedis artery cannulations in adult intensive care unit (ICU) patients. DesignProspective randomized clinical trial. SettingMixed adult ICU of a University Hospital. ParticipantsAdult patients (≥18 years) admitted to the ICU requiring invasive arterial pressure monitoring were included. Exclusion criteria were patients with a pre-existing arterial line and cannulated with other than a 20-gauge cannula for radial and dorsalis pedis artery. InterventionComparison of arterial cannulation by USG versus palpation technique in radial, femoral and dorsalis pedis arteries. Main variables of interestPrimary outcome was first attempt success rate, secondary outcomes were assessing time for cannulations, number of attempts, overall success rate, complications, and comparison of two techniques on patients requiring vasopressor. Results201 patients were enrolled in study, with 99 randomized to DP group and 102 to USG group. Arteries (radial, dorsalis pedis, femoral) cannulated in both groups were comparable (P = .193). Arterial line was placed on first attempt in 85 (83.3%) in USG group versus 55 (55.6%) in DP group (P = .02). Cannulation time in USG group was significantly shorter compared to DP group. ConclusionsIn our study, USG arterial cannulation, compared to palpatory technique, had a higher success rate at first attempt and a shorter cannulation time. Clinical Trial Registry of India numberCTRI/2020/01/022989.