The current status of sample preparation activities and AMS determination of I-129/I ratios are described. Determination of I-129/I ratios is being performed routinely at the precision of 3% (at 10(-11) level). A system background of 20-80 x 10(-15) of I-129/I ratio has been achieved without a time-of-flight (TOF) detector and without a low-energy electrostatic deflector. An intercomparison of I-129/I ratios for AgI samples obtained from other AMS facilities and for the round robin exercise by the International Atomic Energy Agency (IAEA) show an excellent agreement. Potential applications of I-129 for tracing groundwater and ocean water are discussed.