Background <p>The purpose of this study was to determine the association between a decline in 6-minute walk distance after pulmonary resection and prognosis, including hospital re-admission and mortality.</p> Methods <p>This study was a retrospective cohort study, and included 99 patients who underwent pulmonary resection between April 2015 and February 2018 and a 6-minute walk test before and after surgery. The subjects were divided into two groups: those with a ≥30-m decrease in 6-minute walk distance (the decreased group) and those with a &lt; 30-m decrease (the unchanged group). The number of days until hospital re-admission or mortality after discharge was investigated and compared. A Cox proportional hazards model was used to examine the factors affecting hospital re-admission.</p> Results <p>The unchanged group contained 46 subjects, and the decreased group contained 53 subjects. There was no statistically significant difference in clinicopathologic background between the two groups, except for operating time. There were five hospital re-admissions in the unchanged group and 14 in the decreased group, with a significant increase in the decreased group (<i>P</i> = 0.04). There was no significant difference in overall survival between the two groups; however, overall survival tended to be lower in the decreased group (<i>P</i> = 0.07). The results of the Cox proportional hazards model identified a decrease in 6-minute walk distance of 30&#xa0;m as an independent influencing factor affecting hospital re-admission (hazard ratio, 3.05; 95% confidence interval, 1.02–9.15; <i>P</i> = 0.04).</p> Conclusions <p>The results suggest that a reduction of greater than 30&#xa0;m in 6-minute walk distance before and after pulmonary resection is associated with an increased risk of hospital re-admission.</p>