Reliable measurement of Tritium for regulatory and radiological protection purposes requires the design of samplers which are simple to operate and easy to maintain and check during operation. Where measurements of Tritium in only the oxide form suffice, passive (diffusion tube type) samplers are very effective, requiring no moving parts or power supplies for their operation. Where separate measurement of Tritium in the oxide (HTO) and elemental form (HT) is required dynamic samplers, involving pumped gas systems, are generally necessary. Designs of both type of sampler, commissioned by JET, are described and the results of one year's operation, for environmental applications, are presented and discussed.