BackgroundYolk sac tumour (YST) is the second most common ovarian germ cell tumour and usually presents in children and young women. However, tumours rarely occur as malignant gynaecological tumours with YST components.Case presentationWe present one case of endometrioid carcinoma and clear cell carcinoma with YST components and two other cases of YSTs associated with high-grade serous carcinoma of the ovary in females. After surgery and adjuvant chemotherapy, the patient with endometrioid carcinoma had progressive disease and died 20 months later, and the other two were still alive at the last follow-up.ConclusionsTo our knowledge, these mixed neoplasm associations are unusual, and these cases illustrate the diagnosis and prognosis of YST associated with malignant gynaecological tumours, emphasizing early recognition and aggressive treatment.