The hypothesis that shipments of oranges into Japan have displaced, and will continue to displace, domestic Mandarin orange shipments in Japan was tested using annual and monthly data and by estimating an econometric model. It was found that the marketing seasons of Mandarin and imported oranges are substantially different. This result, along with econometric estimates, indicated that Mandarin and imported oranges do not directly compete with each other, and supported rejection of the hypothesis that imported oranges have displaced Mandarin orange shipments. It was projected that, under full trade liberalization, orange imports would increase by 115 percent. However, most of this increase would occur during the April to September period when few Mandarin oranges are shipped.