Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) constitutes a very attractive alternative to radiochemical techniques for the determination of long-lived radionuclides considered critical for the safety of nuclear waste repositories. By measuring isotopic abundance instead of ionizing radiation, it is shown that ICP-MS should exhibit lower detection limits than liquid scintillation counting for the measurement of β emitters with half-lives longer than ∼10⁴ years. However, a specific preparative chemistry is generally required prior to measurement in order to separate the analyte from major radioactive contaminants and potentially interfering isotopes. Original methods we have recently developed for the determination of three long-lived β emitters: ⁹³Zr, ¹⁰⁷Pd and ¹³⁵Cs in radioactive waste are described in this paper. The procedures involve various separative and measurement strategies, such as liquid-liquid extraction, Chromatographic separation as well as electrothermal vaporization coupled with ICP-MS. The performances are discussed in terms of selectivity and detection capabilities.