University of Cincinnati Dyspnea Questionnaire (UCDQ) was developed to measure the impact of dyspnoea during (1) physical activity (Phys), (2) speech activity (Speech) and (3) simultaneous speech and physical activity (Comb). The aim of this study was to evaluate the validity of UCDQ in COPD patients, comparing it to a large set of dyspnoeic indices and functional parameters. Fifty COPD patients (age 58.7 +/- 9.1 years, FEV1%pred = 39.3 +/- 17.0%, Baseline Dyspnoea Index (BDI) = 4.9 +/- 2.5, Six Minute Walk Distance (6MWD) = 373 +/- 128 m, Symptoms score = 9.4 +/- 2.5; mean +/- SD) participated in the study. We found the following mean scores for the three sections of the questionnaire: Phys = 3.5 +/- 0.9; Speech = 2.4 +/- 1.1; Comb = 4.2 +/- 1.0, meaning that patients report the most breathlessness during the combination of speaking and physical activity and the least breathlessness during speech activities. All three section of UCDQ had significant strong correlation with dyspnoea indices (BDI, Borg, MRC, OCD), 6MWD and symptoms score, which proves its concurrent and construct validity. Differentiation of patients by speech section (=3<) discriminated them significantly with respect to all dyspnoeic indices, symptoms score and 6MWD. All three dimensions of UCDQ had high test-retest reliability - ICC between 0.76 and 0.93. Factor analysis yielded three interpretable factors, as all dyspnoeic indices, three sections of UCDQ, symptoms score and 6MWD were loaded on the first factor. In conclusion, UCDQ provides valid and reliable information about the effect of dyspnoea on speech and daily activities.