Hidradenitis suppurativa (HS) is a recurrent, debilitating suppurative skin disease. Nowadays the major challenge is the choice of optimal treatment. Many conservative therapies seem to have only a supportive character and do not prevent progression of the disease. Early surgical intervention with complete excision of the involved areas is still considered to be the most efficient therapy, but anti-tumour necrosis factor (TNF)-alpha agents may offer a possible non-surgical treatment. The aim of this study was to determine the serum concentration of TNF-alpha and its probable alterations during the disease process in patients with HS. Analysis of TNF-alpha serum concentration in 54 individuals with HS revealed significantly higher levels than in the sera of healthy controls (p = 0.006). To the best of our knowledge, this is the first report of increased TNF-alpha serum concentration in patients with HS.