The progress in oncological treatment has led to the current increase of childhood cancer survival rate to 80%. That is why orthodontists more and more frequently consult patients who had completed a successful anti-cancer therapy in childhood. Oncological treatments such as chemotherapy, radiotherapy or supportive immunosuppressive therapy cause numerous side effects in growing patients, connected i.a. with growth, the development of teeth or the viscerocranium. This is a special group of patients that needs an optimised plan of orthodontic treatment and often has to accept a compromise result. The purpose of the current work is to discuss the results of orthodontic treatment in patients after an anti-cancer therapy. Time of treatment was 12,5 months. In 6 patients (from 40 undergoing orthodontic therapy) we haven't reached a normocclusion, in 9 patients we should have stopped the therapy because of the recurrence. In 11 patients we found mucosa inflammation and in 1 patient the therapy stopped before the end because of very low oral hygiene level. Bearing in mind the limited number of original works on the above topic in Polish medical literature, the study has been carried out in order to make Polish orthodontists more acquainted with the topic and the standards of dealing with an oncological patient.