Objective: The individual evaluation of patients’ motivation should be introduced to the protocol of periodontal treatment, as it could impact positively on effective treatment planning and treatment outcomes. However, a standardised tool measuring the extent of periodontal patients’ motivation has not yet been proposed in the literature. Thus, the objective of the present study was to determine the validity and reliability of the Żychlińscy motivation scale adjusted to the needs of periodontology. Basic research design: Cross sectional study. Clinical setting: Department of Periodontology and Oral Medicine, Dental University Clinic, Jagiellonian University, Krakow, Poland. Participants: 199 adult periodontal patients, aged 20–78. Interventions: 14-item questionnaire. The items were adopted from the original Żychlińscy motivation assessment scale. Main outcome measures: Validity and reliability of the proposed motivation assessment instrument. Results: The assessed Cronbach’s alpha of 0.79 indicates the scale is a reliable tool. Principal component analysis revealed a model with three factors, which explained half of the total variance. Those factors represented: the patient’s attitude towards treatment and oral hygiene practice; previous experiences during treatment; and the influence of external conditions on the patient’s attitude towards treatment. Conclusion: The proposed scale proved to be a reliable and accurate tool for the evaluation of periodontal patients’ motivation. Key words: motivation, reliability, validity, periodontal disease