An improved medical device for laser therapy, comprising: - a containment casing, in which at least two laser sources are housed, configured to emit photons having therapeutic action, which have mutually different wavelengths and which are substantially comprised between 550 nm and 1075 nm, and with emission power substantially comprised between 500 mW and 15 W, - at least two first optical fibers, one for each laser source, which are housed in said containment casing and in which the photons emitted by the corresponding laser source are sent, - a single second optical fiber which, at least in part, is external to said containment casing, - a mechanical connection for connecting the output terminals of all said at least two first optical fibers to an input end of said second optical fiber so that the photons output from all said at least two first optical fibers enter into said optical fiber, - an applicator handpiece, which is associated with the other end of said second optical fiber and is provided with an opening, which communicates with said second optical fiber to let out the photons emitted by said laser sources at the tissue to be treated, - a control and processing unit configured to control the activation/deactivation of said at least two laser sources so that they emit said photons simultaneously and/or in sequence, - a user interface for managing the device. and wherein: - said mechanical connection is configured so that, in its interior, the input end of the second optical fiber faces and/or is aligned with the output terminals of all said first optical fibers, - the cross-section area of the second optical fiber either substantially corresponds with or is preferably greater than the sum of the cross-section areas of all the first optical fibers. - a containment casing, in which at least two laser sources are housed, configured to emit photons having therapeutic action, which have mutually different wavelengths and which are substantially comprised between 550 nm and 1075 nm, and with emission power substantially comprised between 500 mW and 15 W, - at least two first optical fibers, one for each laser source, which are housed in said containment casing and in which the photons emitted by the corresponding laser source are sent, - a single second optical fiber which, at least in part, is external to said containment casing, - a mechanical connection for connecting the output terminals of all said at least two first optical fibers to an input end of said second optical fiber so that the photons output from all said at least two first optical fibers enter into said optical fiber, - an applicator handpiece, which is associated with the other end of said second optical fiber and is provided with an opening, which communicates with said second optical fiber to let out the photons emitted by said laser sources at the tissue to be treated, - a control and processing unit configured to control the activation/deactivation of said at least two laser sources so that they emit said photons simultaneously and/or in sequence, - a user interface for managing the device. - said mechanical connection is configured so that, in its interior, the input end of the second optical fiber faces and/or is aligned with the output terminals of all said first optical fibers, - the cross-section area of the second optical fiber either substantially corresponds with or is preferably greater than the sum of the cross-section areas of all the first optical fibers.