To assess the prevalence and the team interaction in cases of missed delirium in acute care veterans coded as not having a diagnosis of delirium in admission or discharge notes. In this retrospective study, the records of 183 hospitalized veterans admitted to the emergency department (ED), medicine, surgery and psychiatry services and coded as not having a diagnosis of delirium were analyzed. Clinical notes of each case were examined using DSM IV TR criteria for delirium. Of the 52 cases assessed to have delirium, 5 cases had been miscoded as not having delirium. In the remaining 47 cases the diagnosis of delirium had been missed. The rates of undiagnosed delirium were ED 46/160, medicine 39/132, surgery 4/17, psychiatry 4/29 and consult liaison (CL) 0/9. Of the 5 cases of delirium identified by the CL service, 2 consult diagnoses were accepted and 3 were rejected. Nursing notes had words suggesting delirium in 70.2 % of 47 cases compared to 41.3 and 43.6 % of the clinician case notes for these patients admitted to ED and medicine respectively. No delirium or cognitive screening scales were utilized in the work up of the 52 cases involving delirium. The study results suggest that continuing education by the CL service of all hospital personnel involved in patient care may improve the diagnosis of delirium. Also, increased clinician-nursing intra-team communication, in addition to careful scrutiny of the nursing and clinician notes may contribute to the reduced incidence of missed delirium.