The civil war in mainland China during 1945-1949 resulted in an enormous influx of immigrants to Taiwan, the majority of whom were single male soldiers in their twenties or thirties. In addition, a military marriage ban prevented most of the immigrant soldiers from getting married until 1959. These two factors have profound, but distinct, influences on the effective prime-age sex ratio in the marriage market in post-war Taiwan. Unfortunately, the official population data in Taiwan excluded the military and thus did not reveal the true male population until the late 1960s. This paper proposes a method to impute the effective prime-age sex ratio. The imputation result shows that the effective prime-age sex ratio first rose in the 1950s, peaked in the 1960s, and then declined in the 1970s. At its peak, as many as 120 men were competing for only 100 women in the marriage market. © 2013 Copyright Taylor and Francis Group, LLC.