Yoncalla is a city in Douglas County, Oregon, United States. The population was 1,052 at the 2000 census.
According to the United States Census Bureau, the city has a total area of 0.6 square miles (1.6 km²), of which, 0.6 square miles (1.6 km²) of it is land and 1.61% is water.
As of the census of 2000, there were 1,052 people, 409 households, and 287 families residing in the city. The population density was 1,728.1 people per square mile (665.9/km²). There were 437 housing units at an average density of 717.8 per square mile (276.6/km²). The racial makeup of the city was 93.92% White, 0.48% Native American, 0.48% Asian, 0.57% Pacific Islander, 1.33% from other races, and 3.23% from two or more races. Hispanic or Latino of any race were 1.90% of the population.