BACKGROUND: It was already evidenced decreased heart rate variability (HRV) in chronic obstructive pulmonary disease (COPD) patients at rest. OBJECTIVE: In order to insert new elements in the literature regarding this issue, we evaluated geometric index of HRV in COPD subjects. METHOD: We analyzed data from 34 volunteers, divided into two groups according to spirometric values: COPD (17 volunteers, FEV1/FVC=47.3+/-10.2; FEV1=50.8+/-15.7) and control (17 volunteers, FEV1/FVC=78.8+/-10.8; FEV1=100.1+/-14.7). For analysis of HRV indexes the volunteers remained in the supine position for 30 minutes. We analyzed the following indexes: triangular index (RRtri), triangular interpolation of RR intervals (TINN) and Poincare plot (SD1, SD2 and SD1/SD2). Student t test for unpaired samples and Mann-Whitney test were used for data analysis. RESULTS: We observed statistically significant reductions in geometric indexes in the COPD group: RRtri (0.043+/-0.01 vs. 0.059+/-0.02; p=0.018), TINN (105.88+/-51.82 vs. 151.47+/-49.9; p=0.014), SD1 (9.76+/-4.66 vs. 14.55+/-6.04; p=0.014) and SD2 (34.86+/-17.02 vs. 51.51+/-18.38; p=0.010). SD1/SD2 (0.30+/-0.11 vs. 0.28+/-0.07; p=0.605) were not significantly different between groups. Patients with COPD presented a visual analysis of Poincare plot of lower dispersion of RR intervals both beat to beat and the long term. CONCLUSION: Subjects with COPD present reduction of geometric indexes of HRV, indicating reduced heart rate variability.