[en] Technetium-99m-HM-PAO [(^99mTc]HM-PAO) leukocyte and indium-111-oxine (111In-oxine) leukocyte scanning were carried out simultaneously in 41 patients at 4 hr and 24 hr after reinjection to determine whether the 4-hr ^99mTc scan could replace the 24-hr ¹¹¹In scan for detecting intraabdominal sepsis. Abdominal infection was confirmed in 12 cases. The 4-hr ⁹⁹Tc-leukocyte scan, the 4-hr ¹¹¹In-leukocyte scan, and the 24-hr ¹¹¹In-leukocyte scan yielded a sensitivity of 100%, 67%, and 100%, respectively, and a specificity of 62%, 90%, and 86%, respectively. The 24-hr ^99mTc-leukocyte scan also produced a sensitivity of 100%, but it was falsely positive in all 29 cases without infection due to physiologic bowel uptake. False-positive 4-hr ^99mTc-leukocyte scans were also produced by physiologic bowel uptake in seven cases all of whom had true-negative 4-hr and 24-hr ¹¹¹In-leukocyte scans. Because of the high incidence of false-positive 4-hr [^99mTc]HM-PAO leukocyte scans, it was concluded that they could not replace 24-hr ¹¹¹In-leukocyte scans for detecting intraabdominal sepsis, and that serial ^99mTc leukocyte scans starting earlier than 4 hr after reinjection must be evaluated