Teams in Japan’s two professional baseball leagues began to add foreign players to their rosters in the early 1950s, with the average number of foreign players per team reaching 5.79 in 2004. One reason for teams’ increased use of foreign players was that foreign hitters substantially outperformed Japanese hitters. This was due in part to binding roster caps on the number of foreign players per team. High performance was coupled with a very short tenure, with median tenure varying between one and two seasons between 1958 and 2004. We find that foreign players were hired either near the beginning or the end of their careers, with the median age of a foreign player exceeding 30 years. Our analysis shows that Japanese teams used foreign players as a “quick fix” to fill important positions in their starting line-ups. Over time, as US and Japanese markets for baseball players changed and became more integrated with others, the characteristics, tenure, and performance of foreign players in Japan also changed. We use a sample with all foreign baseball players who played one season or more in Japan to test hypotheses regarding how changes in the player market would affect baseball players’ age, tenure, and batting performance.