A protection device to be fitted onto a syringe (2) used for injecting radioactive material(s). The radiation protection device includes a tubular radiation protection housing (1) that includes an outer tubular part (15), which constitutes at least a portion of the outer surface (11) thereof, and which is made of an elastomeric material. The tubular portion (15) also includes an annular constrictive portion (20) including a resiliently deformable inner surface that is used to apply a compressive force around the cylindrical body (3) of the inserted syringe (2).