Peh-oe-ji, also known as 'church Roman scripts', 'Taiwanese characters' or 'people's scripts', was a Romanized writing system invented by missionaries for writing Taiwanese and Hakka languages in the second half of nineteenth century. Peh-oe-ji had great influences and made substantive contributions to public education, cultural enlightenment, and literary creations especially in the late nineteenth century and the early twentieth century. This paper surveys the population of Peh-oe-ji users and its usages in the Presbyterian Church in Taiwan through census and field investigation conducted in 2012. A total of 29 Peh-oeji users with the average age of 75.8 were interviewed. Most users learned Pehoe- ji during Sunday school when they were children. They spent an average of 30~60 minutes per week in class. The users usually acquired the reading skills after several classes or months of learning. The investigation also reveals that the population of Peh-oe-ji users declined noticeably starting the 1970s when Taiwanese Peh-oe-ji was no longer prominently taught in church Sunday schools.