Two field experiments were conducted during growing season of 2011-2012 at two locations, 1. Seed and Plant Certification and Registration Research Institute (SPCRI), Karaj-Iran 2. Agricultural and Natural Resources Research Center, Yazd-Iran, to study dry matter accumulation and remobilization in grain wheat (Triticum aestivum L.) cultivars under drought stress and potassium foliar application treatments. The experiment was carried out using a split plot factorial based on a randomized complete blocks design with three replications. The experimental treatments included three irrigation regimes; normal, mild stress (water withhold at the seed filling phase) and severe stress (water withhold at the ear emergence phase); potassium foliar treatments included, 0, 1.5% and 3.0% K2O applications and three wheat cultivars (Marvdasht, Pishtaz and WS-82-9). The amount of remobilized dry matter (ARDM), remobilization efficiency (REE), remobilization percentage (REP) and grain yield were measured. The results showed that water stress significantly increased amounts of remobilized dry matter, remobilization efficiency and remobilization percentage compared with normal condition in both locations. However it significantly decreased grain yield. Foliar application of potassium at the rate of 3.0% K2O gave the highest values of all studied wheat characters followed by 1.5% K2O as compared with control treatment in both locations. Marvdasht cultivar had the lowest values of the above mentioned characters as compared with the two other cultivars.