Abstract: A multifunctional continuous dyeing apparatus provided at a bottom with a main body within which are formed in a sequence, with reference to the feeding direction of the yarn, at least a first dyeing group for the yarn, provided with a respective first squeezing device of the yarn, an oxidation or diffusion/fixation group, placed downstream of the first dyeing group and arranged for the oxidation of the dyed yarn or for the diffusion/fixation of the dye in the fiber of the dyed yarn, and at least a second dyeing group of the yarn, arranged downstream of the oxidation or diffusion/fixation group and in turn provided with a respective second squeezing device of the yarn, where at least the first dyeing group, the first squeezing device, the oxidation or diffusion/fixation group and the second dyeing group are hermetically sealing enclosed by at least one covering case, integral at the top with the main body, and provided with a plurality of doors which are at least partially openable to perform the dyeing of th