•The incidence of radiation-induced malignancies appears to be increasing as cancer survivorship improves.•This is a rare case of radiation-induced pleomorphic sarcoma with rhabdomyoblastic differentiation.•Radiation-induced malignancies generally have poor prognosis.•Clinicians must have a high index of suspicion to detect these cases early to facilitate timely treatment. We present the case of a 59-year-old woman who developed a right thigh pleomorphic sarcoma with rhabdomyoblastic differentiation 6 years following radiotherapy for a vaginal squamous cell carcinoma. The overall 5-year survival for a gynaecological malignancy is more than 80 % and as overall cancer survivorship and life expectancy improves, the incidence of radiation-induced malignancy is increasing (Bjerkehagen et al., 2013). As the prognosis of those malignancies is usually poor, clinicians must have a high index of suspicion to try to detect these cases early.