The objective of this research was to evaluate the efficiency of two kinds of plastic packages to avoid seed moisture changes with the environment, and to determine the moisture content seeds may be stored by 240 days into those packages without seed quality reduction. Dry (Phaseolus) bean seeds cv. Guateian-6662 with 9.6, 10.3, 11.3 and 12.4 moisture content were stored from april to december 1991 in 0.15mm - plastic bags and 20 liters - plastic bottles in a conventional storage facility located at Pelotas, Rio Grande do Sul state, Brazil. Moisture content determinations and physiological quality evaluation (standard germination, accelerated ageing, eletrical conductivity and field emergency) were performed every 30 days in the first four months of storage and every 15 days the atest 4 months. The results allowed to get the following conclusions: a) 0,15mm - plastic bags and 20 liters - plastic bags were efficient in maintaining seed moisture content without fluctuations in the range of 9,6 to 12,4% all over the storage period; b) those sealed packages were equivalent and efficient in maintaining physiological quality of bean seeds stored through 240 days with seed moisture contents up to 12,4%; c) seed moisture contents up to 12% were reliable to preserve standard germination, storage potential and field emergence capacity of bean seed from april to december open storage period in Pelotas, RS, Brazil.