579 Background: Atezolizumab plus bevacizumab and lenvatinib have not been compared in a randomized controlled trial. We conducted a retrospective multi-center study to compare the clinical efficacy and safety of lenvatinib and atezolizumab with bevacizumab as a first-line treatment for patients with unresectable HCC in the real-world scenario. Methods: Clinical features of lenvatinib and atezolizumab plus bevacizumab patients were balanced through inverse probability of treatment weighting (IPTW) methodology, which weights patients' characteristics and measured outcomes of each patient in both treatment arms. Overall survival was the primary endpoint. Results: The analysis included 1,341 patients who received lenvatinib, and 864 patients who received atezolizumab plus bevacizumab. After IPTW adjustment, atezolizumab plus bevacizumab did not show a survival advantage over lenvatinib HR 0.97 (p=0.739). OS was prolonged by atezolizumab plus bevacizumab over lenvatinib in viral patients (HR: 0.76; p=0.024). Conversely, OS was prolonged by lenvatinib in patients with NASH/NAFLD (HR: 1.88; p=0.014). In the IPTW-adjusted population, atezolizumab plus bevacizumab provided better safety profile for most of the recorded adverse events. Conclusions: Our study did not identify any meaningful difference in overall survival between atezolizumab plus bevacizumab and lenvatinib. Although some hints are provided suggesting that patients with NASH/NAFLD might benefit more from lenvatinib therapy and patients with viral etiology more from atezolizumab plus bevacizumab.