A harness (10) for pets, typically for dogs (30), comprises a first elongate and shaped front strap (11) designed to be fitted on the chest area, a second elongate and shaped rear strap (12) designed to be fitted on the abdominal area, and an element (13) connecting the above-mentioned first (11) and second (12) straps, designed to be fitted on the animal's back. Each end of the front strap (11) is connected to a corresponding end of the rear strap and to an end of the connecting element (13) at a pin (16, 17) which allows the straps (11, 12) to move relative to each other adapting anatomically to the body of the animal and thus forming a harness suitable for animals of different sizes.