This study aims to assess accuracy in detecting patient presence or absence by using a bed sensor based on mmwave radar technology above the patient bed. Methods: Patients and healthy volunteers were observed during their presence or absence in a bed in hospital and home location. These observations were compared with data coming from bed sensor monitoring patient presence using tina.care® bed sensor ASWA. Results: A total of 53 different observations were performed during the study period and the bed sensor reached accuracy of 94%, precision of 90%, sensitivity of 99% and specificity of 89% to detect presence or absence of patients in a bed. Conclusions: The sensor demonstrated strong performance in detecting patient presence in bed, with reasonable specificity and low false negatives. Further research should assess bed-exit and bed-entry events, system's accuracy in a larger cohort, its impact on patient care, and the precision of vital health parameters measured by the sensor in order to compare it with similar studies.