Teeth discoloration is a rare orthodontic complication during orthodontic treatment. We present 6-year clinical obser- vation conducted from January 2010 till December 2016. The eighteen orthodontic patients with teeth discoloration took part in this observation. Four patients were excluded from the observation as their teeth discoloration were under orthodontic treatment. During clinical observation period, discovered discoloration was evaluated as «improved» in 4 out of 14 teeth (28.5 %), as «maintained» in 10 teeth (71.4 %). Electroodontodiagnosis conducted during the initial detection period of discoloration showed 14.3 % positivity, which improved to 21.4 % at the final follow-up. The radio- logical pictures of the teeth showed no abnormalities. Thus, we can assume that teeth with one wide long root canal are more prone to damage to the pulp blood supply. Discoloration is also more frequent in the maxillary teeth, possibly due to the overjet relationship, which may increase susceptibility to trauma in the maxillary teeth. We should keep dynamical observation in the orthodontic practice as teeth color could reverse to the initial without additional interference. If discoloration does not improve even after sufficient observation, it is necessary to start or- thodontic treatment (endodontic, prosthetic) or bleaching. A patient should be informed that discoloration does not always indicate devitalization or pulp necrosis. Instead of “devitalization” or “pulp necrosis” we recommend to use the term “discoloration”.