Abstract: An analytical method is developed for the determination of Ra in water bymeans of α--counting after Ra has been coprecipitated first with PbSO_4 and thenwith BaSO_4 in EDTA--NH_4OH with a recovery of ～99%. Lower limit of thedetermination is 2.7×10~(-4) Bq/1 by the use of instruments having low Ra--background≤1.3×10~(-5)Bq. The determination takes 5 hours in case the ratio ~(226)Ra/~(224)Ra (B value) isknown. If B value is not known, another determination is necessary after thesample is allowed to decay for at least 40 hours to give the amounts of ~(226)Ra and~(224)Ra.