The Issei Japanese Americans (一世 lit. first generation) are Japanese Americans who arrived in the United States before the Immigration Act of 1924.

The Issei were brought to the United States as a replacement supply of cheap labor due to the Chinese exclusion Act's restriction on Chinese immigrants. The loop hole was later plugged to stop Japanese immigration also as a protectionist measure. The Issei were very successful in improving on rice farming on poor soil. Japanese Californian farmers made rice a major crop of the state. The largest Issei community settled around Vacaville, California near San Francisco.

All Issei living in the western United States were forcibly interned with their children (Nisei Japanese Americans) and grandchildren (Sansei Japanese Americans) during World War II.