Stomach cancer is the second most common cancer in Eastern Asia, accounting for approximately 50% of all new cases of stomach cancer worldwide. Our objective was to compare the stomach cancer incidence rates of Asian Americans in Los Angeles with those of native Asians to assess the etiology of stomach cancer from 1988 to 2011. To examine these differences, Asian Americans (Korean, Japanese, Chinese, and Filipino Americans living in Los Angeles, California, USA) and native Asians (from Korea, Japan, China, and the Philippines) were selected for this study. Using the Cancer Incidence in Five Continents database, stomach cancer incidence rates were examined. Data from the National Cancer Registry of Korea were used for native Koreans. Between native countries, the incidence rates in Japan, China, the Philippines, and the US declined over time, but the incidence in Korea has remained constant. The incidences among Asian immigrants were lower than those among native Asians. The incidence rates of males were approximately 2 times higher than those among females in Asian countries were. The effect of immigration on stomach cancer incidence suggests that lifestyle factors are a significant determinant of stomach cancer risk. However, the incidence in Korea remains the highest of these countries