Altered passive eruption is one of the causes of an aesthetically unfavorable relationship between the gingiva and the clinical crown of the tooth, which often manifests itself as a “gummy smile“. It is characterized by excessive visibility of the gingiva above the crown of the tooth, which prompts patients to seek therapy in order to restore pleasing facial and smile aesthetics. The exact mechanism of altered passive eruption is not known, but possible genetic, hormonal, mechanical, and morphological factors are mentioned in the etiology. Diagnostic procedures such as transgingival probing, bone probing, and radiological methods can correctly determine which type of altered passive eruption one is affected by. In doing so, the Coslet classification is used, recognizing 4 subtypes of altered passive eruption: 1A, 1B, 2A and 2B. The method of treatment is chosen depending on the subtype. The therapy for altered passive eruption consists exclusively of surgical methods that restore the harmonious relationship between soft and hard tissues making up a smile. In the case of type 1A, gingivectomy is sufficient, and the use of aids in order to achieve the highest possible precision is also recommended. The therapy for other subtypes combines ostectomy and osteoplasty with an apically repositioned flap, with the aim of allowing the bone to form a sufficient width of the keratinized gingiva to make the result as high quality and long-lasting as possible. Before planning the therapy, other possible factors that result in excessive visibility of the gingiva should be ruled out in order to be sure what cause we need to act on, whether there are multiple causes, and whether there is the need for a multidisciplinary approach. By following diagnostic procedures and keeping their shortcomings in mind, we can relatively easily arrive at an accurate diagnosis in each individual case and choose the method of treatment accordingly.