Interest in using high tunnels for producing red raspberries is increasing in temperate climate regions of the United States. High quality fruit can be produced under tunnels but the profitability of this system has not been investigated in Michigan under current economic conditions. Additionally, no work has been done to describe how the use of a 3-season tunnel during the growing season may influence cold hardiness during the winter. Objectives of this work were to: (1) determine the profitability of floricane- (FF) and primocane-fruiting (PF) raspberry cultivars in tunnels under certain costs and berry prices, (2) characterize cold acclimation of high tunnel-grown raspberry plants, and (3) determine carbohydrate levels in acclimating plants and describe their relationship to cold hardiness. Crop values at full production for one acre of FF and PF tunnel raspberries were $60,060 and $71,520, respectively. Break-even yields (yields necessary to cover costs) for PF types were lower than for FF types, indicating PF cultivars have a higher potential for profit under tunnels. Cold hardiness of tunnel and field raspberry tissues were similar on most dates in the autumn, suggesting cold acclimation under covered, 3-season tunnels and in the field may be similar. Bud primordia and cambium tissues of ‘Nova’ were typically more cold hardy than ‘Canby’ and ‘Encore’ during acclimation and in mid-winter. Concentrations of the soluble carbohydrate raffinose were higher in ‘Nova’ than the other two cultivars. All soluble carbohydrate levels were positively correlated with hardiness while starch was negatively correlated. Early high tunnel plastic removal increased hardiness of bud primordia but had no effect on cambium hardiness.