This article explores the factors that affect a farmer's decision to purchase seed potato in East Java. The research draws on a survey of 209 farmers from three central production areas: Pasuruan, Probolinggo and Batu Malang. Farmers were asked to rate the importance of 34 variables believed to influence a farmer's decision to purchase seed potatoes. The results reveal that the availability of seed at planting time, along with the availability of resources such as land and labour, are the most important factors influencing farmers' decisions to purchase seed. The lack of good quality seed available at planting time means that farmers are often forced to plant whatever seed is available. As a result, farmers typically use their own seed—retaining around 15-20 per cent from the previous harvest—until it degenerates. Only then do farmers tend to purchase improved seed. Given that demand for potato seed in Indonesia outstrips supply, potato farmers still rely heavily on high quality imported seed. However, the high cost of imported seed means that most farmers buy seed from their local supplier that has been multiplied several times.