Chemo-immunotherapy (CIT) with platin, etoposide and monoclonal antibodies targeting the PD-1/PDL-1 pathway has recently improvedsurvival in extensive-stage small-cell lung cancer (SCLC) after decades. We aimed to investigate the efficacy and safety ofCIT with atezolizumab in extensive-stage SCLC in chemotherapy naïve patients. Eleven patients who were treated and followed inour center were included in this retrospective observational study. All the patients received carboplatin, etoposide and atezolizumabin the induction phase and atezolizumab in the maintenance phase. The Kaplan–Meier test was used to determine progression-freesurvival (PFS) and overall survival (OS), and the effects of the sites of metastasis were analyzed using the log-rank test. The medianage was 69.9 years, and 81.8% were male. The median number of CIT and total atezolizumab cycles was 4 and 7, respectively.63.6% received maintenance therapy. Median PFS was 5.2 months (95% CI: 3.4-6.9), and median OS was 11.3 months (95% CI:1.0-21.5). The overall response rate was 63.6%. There was no significant difference between patients with and without liver metastasisin terms of PFS and OS. We observed toxicity higher than grade 2 in more than half of the patients, and hematological toxicitieswere prominent. CIT with carboplatin, etoposide and atezolizumab is efficient and safe in extensive-stage SCLC considering the PFS,OS, response rates, 12-month survival rate, and side effects. The progression of liver lesions was remarkable. Cranial and thoracicradiation are issues that should be discussed in the future with data from clinical studies.