Background: Pulmonary changes and their respiratory consequences in patients with chronic obstructive pulmonary disease (COPD) could lead to many physical complications and are one of the major causes of hospitalization. Objectives: In this regard, the present study explores the efficacy of self-care training on spirometric indices of COPD patients. Methods: This clinical trial was performed on 70 patients with COPD who had been admitted in 2017 to Ali Ibn Abi Talib Hospital in Zahedan, Southeast Iran. The subjects were recruited through convenience sampling based on the inclusion criteria and were subsequently randomized to the intervention and control groups. The self-care program was administered to the intervention group during eight 30-minute sessions organized within 4 weeks. Data collection tools included a demographic questionnaire and Vitalograph Alpha Spirometer. Data were analyzed in SPSS V. 21 using chi-square, Independent t-test, and Paired t-test at the significance level of 0.05. Results: The results of 8 sessions of self-care training revealed that the mean FVC index of patients before self-care education was 43.40 ± 8.54 in the intervention group and 46.54 ± 10.73 in the control group. After the educational program, the mean score of this index changed significantly in the intervention group (48.62 ± 9.30) (P = 0.01), but no such alteration occurred in the control group (47.11 ± 10.27) (P = 0.16). Furthermore, the mean FEV1 index of the two groups differed significantly after the self-care program (P = 0.01). Conclusions: Given the impact of self-care training on improving spirometric indices in patients with COPD, it is recommended that nurses help ameliorate breathing status of these patients and relieve their symptoms by providing them with self-care instructions.