Purpose In the ToGA trial for HER2-positive advanced gastric cancer, cisplatin plus fluoropyrimidine was given for 6 cycles; trastuzumab was given until disease progression. However, there is a lack of real-life data about trastuzumab maintenance after 6 cycle chemotherapy. This study aims to present real-life data of trastuzumab +/- capecitabine maintenance after 6 cycles of platinum, fluoropyrimidine, and trastuzumab in non-progressive patients. Methods This is a retrospective multicenter study of the Turkish Oncology Group. A total of 35 HER2-positive, inoperable locally advanced, recurrent, or metastatic gastric adenocarcinoma patients being non-progressive at the end of 6 cycle chemotherapy and being given trastuzumab +/- capecitabine as maintenance treatment were included from sixteen oncology centers. Baseline characteristics, objective tumor responses, progression free and overall survival data, and toxicities were determined. Results About 68% of the patients were given CF, and 32% were given FOLFOX with trastuzumab as the first-line treatment. The best response in 6 cycle chemotherapy was complete 8 (22%), partial 24 (68%), and stable disease 3 (8%). All patients had trastuzumab maintenance (median cycle 13; range 7-51), and 49% of the patients had capecitabine with trastuzumab (median capecitabine cycle 6; range 2-30). The median PFS of the patients was 12.0 months (95% CI 10.3-13.7), and median OS was 17.4 months (95% CI 15.2-19.5). There were 2 patients with grade 1 cardiotoxicity. Conclusion Trastuzumab maintenance +/- capecitabine after 6 cycles of trastuzumab plus combined chemotherapy treatment revealed efficacy and safety in non-progressive HER2-positive advanced gastric cancer.