Future studies regarding rehabilitation for patients with ME/CFS may include objective in addition to self-reported outcome measurements. This would allow investigation of the effect of rehabilitation on established physiological dysfunctions in patients with ME/CFS, especially those potentially relating to rehabilitation effects. For instance, autonomic nervous system dysfunction has been demonstrated repeatedly in patients with ME/CFS [14– 17] and may respond to the mindfulness and body awareness sections of the rehabilitation programme. This might also be the case for other abnormal aspects of the stress response system in ME/CFS, including the dysfunctional hypothalamus–pituitary–adrenal axis [18, 19]. With regard to the grading of physical activity levels in the rehabilitation protocol of Vos-Vromans et al. [5], it would have been interesting to examine the possible impact upon established markers of immune hyper-responsiveness to exercise. Following exercise, ME/CFS patients have more pronounced complement system (i.e. elevated C4a split product levels) and oxidative stress system responses (i.e. enhanced oxidative stress combined with a delayed and reduced antioxidant response), and alteration of the gene expression profile of immune cells [20– 23]. Although these immune responses to exercise are known to be related to symptoms of postexertional malaise in patients with ME/CFS [20], it remains unclear whether they are normalized following (multidisciplinary) rehabilitation.