The Acute Project is a research project conducted on acute psychiatric admission wards in Norway. The objective is to develop and validate a structured, easy-to-use screening checklist for assessment of risk for violence in patients both during their stay in the ward and after discharge. The Preliminary Scheme 33 is a 33-item screening checklist with content domain inspired by the Historical-Clinical-Risk Management Scheme (HCR-20), the Brøset Violence Checklist, and eight risk factors extracted from the literature on risk assessment. The Preliminary Scheme 33 was designed and tested in two steps by a research group which includes the authors. The common aim of both steps was to develop this into a time economical, reliable, and valid checklist. In the first step in 2006 the predictive validity of the individual items was tested. The present work presents results from the second step, a study conducted to assess the interrater reliability of the 33 items. Eight clinicians working in an acute psychiatric unit volunteered to be raters and were trained to score the 33 items on a three-point scale in relation to 15 clinical vignettes, which contained information from 15 acute psychiatric patients' files. Analysis showed high interrater reliability for the total score with an intraclass correlation coefficient (ICC) of .86 (95% CI: 0.74-0.94). However, a substantial proportion of the items had medium to low ICCs. Consequences of this finding for further development of these items into a brief screen are discussed.