['To determine whether during the initial phase of head and neck cooling, jugular bulb temperature (Tjb; which may reflect brain temperature) is lower than esophageal temperature (Tes).', 'To compare Tes and Tjb, patients received head or head and neck cooling after cardiac arrest.', 'The first series with head cooling (n = 5; mean age 54 with a range of 41-62 years; 1 female and 4 males; mean body weight 80 kg with a range of 70-85 kg) showed a mean difference of 0.22 degrees C (95% CI, -1.14 to 0.70; P = .55; limits of agreement, -3.17 to 2.73) between Tes and Tjb over 12 hours. For the second series, with head and neck cooling (n = 6, mean age 65 with a range of 56-76 years; 3 females and 3 males; mean body weight 75 kg with a range of 65-91 kg), Tjb was lower than Tes with a difference of 0.60 degrees C (95% CI, 0.22 to 0.99; P = .01; limits of agreement, -3.10 to 4.30). During the first 3 hours, Tjb decreased faster than Tes (1.1 degrees C/h [95% CI, 0.4 to 1.8; P < .01]).'] Does head and neck cooling after cardiac arrest result in lower jugular bulb than esophageal temperature?