After inclusion of four patients, two experienced moderate worsening of symptoms

The hypothesis is that a subset of patients with chronic fatigue syndrome/ myalgic encephalomyelitis (CFS/ME), including also patients with no clinical response after B-cell depletion therapy using the anti-CD20 antibody Rituximab, may benefit from tumor necrosis factor-alpha inhibition using Etanercept as weekly subcutaneous injections.

Inclusion Criteria:

• chronic fatigue syndrome/ myalgic encephalomyelitis (CFS/ME)
• moderate and serious CFS/ME severity
• age 18-66 years
• informed consent

Exclusion Criteria:

• patients with fatigue, not fulfilling criteria for CFS
• pregnancy or lactation
• previous malignant disease, except basal cell carcinoma of skin and cervical carcinoma in situ
• previous long-term systemic treatment with immunosuppressive drugs such as cyclosporine, azathioprin, mycophenolate mofetil, except steroids e.g. in obstructive lunge disease.
• demyelinating disease, such as multiple sclerosis.
• heart failure.
• endogenous depression.
• lack of ability to comply to the protocol.
• multi-allergy with risk of serious drug reaction
• reduced renal function (creatinine > 1.5 x UNL)
• reduced liver function (bilirubin or transaminases > 1.5 x UNL)
• HIV positivity. Evidence of clinically significant infection. Previous viral hepatitis with risk of reactivation. High risk of opportunistic infections. Latent tuberculosis must be treated before inclusion.