Abstract: An underground storage environment for yam tubers was designed and constructed at the college of Engineering, university of Agriculture, Makurdi. The structure which was tested between November 2011 and January 2012, consisted of walls made of burnt bricks, erected from the ground soil level of the underground pit. Thatch and bamboo sticks were used for roofing. Yams were stored in the underground pit structure and also in an open shed for comparison. Test results showed that temperature and humidity in the underground structure ranged from 28.77 oC to 32.70 oC and 70 % to 88 % respectively for 56 days, while that of the open shed fluctuated between 32.90 oC to 36.40 oC and 50 % to 78 % within the same period. The ambient temperature at the location of the storage structure was between 36.40 oC to 40 oC. The reduced temperature achieved in the underground pit together with the average relative humidity, made it possible to store yam tubers for 56 days. In the shed environment however, yams could stay for 35 days.