A 3-mo prospective, longitudinal, repeated-measures study was undertaken in subjects with chronic obstructive pulmonary disease (COPD). The study aimed to determine whether there was a difference in 6-min walk distance (6MWD) when two 6-min walk tests were performed after pulmonary rehabilitation (n = 44) and at 3-mo follow-up (n = 40), and whether the results reflected the program outcomes. There was a significant increase in 6MWD between two 6-min walk tests before rehabilitation (P < 0.001), and at 3-mo follow-up (P < 0.001), but not immediately after rehabilitation (P = 0.1). In terms of program outcomes, there was an increase in 6MWD from before to after pulmonary rehabilitation (P < 0.001); however, the increase was greater if the better of two tests was reported. Six-minute walk tests performed twice before and after pulmonary rehabilitation programs and at 3-mo follow-up assessments ensure accuracy of measurement of the 6MWD and program outcomes.