BACKGROUND: In line with previous findings, in a recent randomized controlled trial (RCT), we found that home treatment (HT) for acute mental health care can reduce (substitute) hospital use among severely ill patients in crises. This study examined whether the findings of the RCT generalize to HT services provided under routine care conditions. METHODS: We compared patients who received HT during the RCT study phase with patients who received the same HT service after it had become part of routine mental health services in the same catchment area. Sociodemographic and clinical characteristics as well as service use (HT and hospital bed days) were compared between the RCT and the subsequent routine care study period. RESULTS: Compared to patients who received HT during the RCT, routine care HT patients were more often living with others, less often admitted compulsorily, more often diagnosed with anxiety and stress-related disorders (ICD-10 F4) and less often diagnosed with schizophrenia spectrum disorders (F2). When compared to patients who were exclusively treated on hospital wards, involvement of the HT team in patients' care was associated with a clear-cut reduction of hospital bed days both during the RCT and under routine care conditions. However, unlike during the RCT study period, involvement of HT was associated with longer overall treatment episodes (inpatient + HT days) under routine care conditions. CONCLUSIONS: HT seems to reduce the use of hospital bed days even under routine care conditions but is at risk of producing longer overall acute treatment episodes.