Bioassay for individual radionuclides is an essential and first step in estimation of radiation risk to nuclear facilities workers and people who are exposed to the contaminated environment in the event of a nuclear accident or radiological attack. Urine is a frequently used biological sample for this purpose. Tritium and (14)C are important radionuclides for workers in nuclear reactors and radiopharmaceutical laboratories. A method for the determination of tritium and (14)C in organic and inorganic forms in urine has been developed. It involves activated charcoal absorption of organic matter followed by combustion to separate tritiated water from organically-bound tritium. Inorganic (14)C from organically-bound (14)C, the separated tritium and (14)C were measured using liquid scintillation counting. Iodine-129, a long-lived beta emitter, is normally released to the atmosphere during the operation of nuclear facilities, especially in reprocessing plants. The high concentration of iodine in the thyroid makes this radionuclide an important source of exposure to exposed populations. A simple method has been developed in this work for the determination of (129)I in urine by anion exchange preconcentration, extraction purification and liquid scintillation counting. Using accelerator mass spectrometry, urine samples can be analyzed for low level (129)I in both organic and inorganic forms after active charcoal adsorption and solvent extraction separation. Condensed water collected daily from the reactor hall in a Danish research reactor and monthly urine samples from the staff working in the reactor building were collected from 2003-2010 and analyzed using this method, and the results are presented and discussed.