BACKGROUND: Heart disease is one of the non-communicable diseases that cause the highest mortality. Its symptoms affect the patient's functional capacity and activities. The six-minute walking test can be done to assess a person's functional ability, response to therapy, and prognosis of chronic heart-lung conditions. The study aims to determine the safety of the six-minute walking test in inpatients after percutaneous coronary intervention by assessing the response of vital signs, Borg scale, and angina scale. METHODS: This study was a one-group pre-and post-test design study with subjects of inpatients after percutaneous coronary intervention at the Integrated Cardiac Service in Cipto Mangunkusumo General Hospital Jakarta. Research subjects conducted a six-minute walking test twice with a five-minute break in between. Examination of vital signs, Borg scale, and angina scale before and after walking test. The number of subjects was 30 (27 male and 3 female) with the majority classified as a low-risk stratification. RESULTS: The six-minute walking test was performed over two days or more in 56.7% of the subjects. The mean covered distance was 294.68 ± 57.02 meters. Vital signs of systolic and diastolic blood pressure, pulse rate, respiratory rate, and Borg rating of perceived exertion (RPE) scale increased during the test. They decreased to baseline after resting for five minutes with p-value <0.05 in the Wilcoxon Signed Rank test. Changes in saturation, dyspnea, and leg fatigue of the Borg scale, and angina scale were not statistically significant. All study subjects did not have major adverse events. CONCLUSION: The six-minute walking test is safe to do in inpatients after percutaneous coronary intervention with vital signs, Borg scale, and angina scale change accordingly to physiological response.