Treatment of gestational trophoblastic disease (GTD) with chemotherapy is a success story for medical oncology; a combination of chemosensitive disease with a sensitive tumour marker makes GTD an eminently curable disease. However, 0·5-5·0% of women with this cancer continue to die as a result of multidrug resistance. PD-L1 is strongly expressed in these tumours, making them a target for immune therapy with immune checkpoint inhibitors such as pembrolizumab. We present two challenging cases of gestational choriocarcinomas, resistant to multiple interventions including multiple lines of chemotherapy, surgery and radiation, who are in long term remission after pembrolizumab immunotherapy. Immunotherapy is a potent weapon in the treatment of GTD and should be considered earlier option as it has the potential to alter the natural history of refractory choriocarcinoma with possible cure.