Actinomycosis is a very rare cause of inflammation of the labial soft tissue in girls. It is characterised by hard inflammatory infiltrates accompanied by fibrosis, abscesses and fistulas. The non-specific course of the disease makes a correct diagnosis difficult. In this paper, we have presented diagnostic and therapeutic difficulties in the inflammation of the labial soft tissue of probable actinomycotic aetiology in a 7-year-old girl. The patient was hospitalised twice, including three surgical procedures due to labial tissue inflammation and abscess. Methicyllin-resistant Staphylococcus aureus was cultured from the abscess content. Systemic antibiotics from six different classes were used; however, no improvement in the local condition was achieved. The abscess was irrigated with gentamicin solution; steroid ointments and physical therapy were used, but with no effect. A suspicion of actinomycotic infection was raised due to the chronic course of the disease and poor response to treatment. Penicillin was administered for a total period of 3 months, resulting in rapid improvement and, ultimately, a complete recovery of the child. Although the actinomycotic aetiology was not confirmed by cultures or histopathological examination, the course of the therapy has allowed to suspect Actinomyces infection.