[en] Internal dosimetry which refers to dosage estimation from internal part of an individual body is an important and compulsory component in order to ensure the safety of the personnel involved in operational of a Nuclear Power Program. Radionuclides particle may deposit in the human being through several pathways and release wave and/or particle radiation to irradiate that person and give dose to body until it been excreted or completely decayed from the body. Type of radionuclides of concerning, monitoring program, equipment's and technique used to measure the concentration level of such radionuclides and dose calculation will be discussed in this article along with the role and capability of Malaysian Nuclear Agency. (author)