Therapy-related acute lymphoblastic leukaemia (t-ALL) is a poorly defined entity and is not featured in the World Health Organization classification as a distinct clinical entity from acute lymphoblastic leukaemia (ALL), thus differing from therapy-related acute myeloid leukaemia and myelodysplasia. We present a case of t-ALL occurring 18 months after treatment for metastatic endometrial cancer with a regimen of carboplatin, paclitaxel and radiotherapy. The patient presented with severe pancytopenia and diagnosed with common-B ALL, and the cytogenetic analysis showed a previously unreported deletion in chromosome 19 (q13.1) in 100% of the blast cells. The patient declined further therapy and died 1 month later. This rare but serious side effect of chemo-radiotherapy should be considered when deciding on treatment options for gynaecological cancers.