Objectives: This study aims to analyse the level of distress caused by delirium in patients' family and their nurses, and to identify factors associated with psychological distress in families of older adult inpatients in Intermediate Care Units/IMCUs regarding their global experience during hospitalization. Method: A prospective pilot study was carried out with families and nurses of older adult patients (≥65 y.o.) consecutively recruited from two IMCUs in Intensive Care Medicine Service in a University Hospital. Patients with Glasgow Coma Scale ≤11, brain injury, blindness/deafness and inability to communicate were excluded. Delirium was daily assessed with Confusion Assessment Method/CAM. The distress level regarding this episode in family and nurses was measured with Delirium Experience Questionnaire/DEQ. Family psychological distress of all recruited patients was assessed with Kessler Psychological Distress Scale/K10. Results: This study included 42 inpatients (mean age/MA = 78 y.o., 50% women), 32 families (68.8% sons/daughters, MA = 50.6 y.o., 81.3% women) and 12 nurses caring for delirium patients (MA = 33 y.o., all women). A total of 12 (28.6%) patients had delirium. Distress related to this episode were higher for families than for nurses (M = 3 vs. M = 2), but differences did not reach statistical significance (Z = –1.535, p = 0.125). The hierarchical regression model explained 44.3% of variability in family psychological distress. Higher levels of psychological distress were associated with living with the patient (p = 0.029), presence of previous cognitive decline (p = 0.048) and development of delirium (p = 0.010). Conclusion: These preliminary results show that family psychological distress is higher, when older adult patients developed delirium during hospitalization. Particular attention to these family carers should be given in future development of psychological support and psychoeducational interventions.