In the past, relatively few studies have been directed at the improvement of the post-harvest storage of fresh yams (Dioscorea spp.). The problems associated with the trading, transportation, and marketing of yams have been largely overlooked. This paper summarises the initial findings of a market characterization survey conducted at Techiman, one of the largest yam markets in Ghana. The marketing system and the trading practices of the principal agents operating within the system are described. Traders cite transportation costs, seasonality of production, poor market infrastructure, lack of credit, mechanical damage, and rotting of tubers as their main constraints. Observations suggest that, during the early season, the loss of yam quality is associated with certain pre-harvest infestations of nematodes and termites as well as a systemic internal browning; post-harvest tissue damage associated with the stacking of tubers, various rots, and the prolonged exposure of tubers to intense sunlight in the market place are subsequent factors. Such deterioration may lead to price discounting of 25-63% and absolute biological losses of 10%.