Hidradenitis suppurativa (HS) is chronic inflammatory skin disease that is more common in women, especially during puberty and menopause. Other disease names include purulent hidradenitis (L73.2 by ICD-10), acne inversa, follicular occlusion syndrome. Clinical picture of the disease is represented by painful, deeply located nodes and abscesses, as well as fistulous tract and fibrous scars. HS mostly localized in axillary cavities, inframammary area, groins, buttocks and perineal region. Diagnosis establishment is based on clinical features, including the following criteria: typical morphology, lesions’ localization and recurrent course. Early HS diagnosis leads to timely prescription of treatment depending on severity by Hurley. The article is devoted to the main disease aspects, including etiology, epidemiology, pathogenesis, classification, differential diagnosis, complications, comorbid diseases, prognosis and effective treatment methods. The clinical report of HS complicated by viral hepatitis C and rare bacterial infection, namely actinomycosis, is presented. Actinomycosis can be considered as an opportunistic infection with consideration to the increasing number of immunocompromised patients (for example, HIV positive or patients with viral hepatitis) and the numerous reports of actinomycotic infection in this conditions. It is known that the gold standard of actinomycosis laboratory diagnosis is a bacteriological (cultural) examination. Nevertheless, the results of a cultural examination can be false-negative in 50% of cases, especially after starting antibacterial therapy. It is important to note that anaerobic actinomycoses are associated with refractory to treatment and recurrent infections of skin and soft tissues.