Exposure to methotrexate in utero can result in fetal methotrexate syndrome - a condition characterised by prenatal-onset growth retardation, craniosynostosis, dysmorphic facies and multiple limb abnormalities. A literature review was prompted by the findings in a girl who is presented here with full consent from her guardian. She is the third child of unrelated parents and was 4 years old at the time of this report. Her mother took 15 mg methotrexate on two occasions during early pregnancy for juvenile idiopathic arthritis, unaware that she was pregnant. This case exhibits many of the classic features of fetal methotrexate syndrome as well as radiohumeral synostosis, which has not previously been described in fetal methotrexate syndrome. The combination of craniosynostosis and radiohumeral synostosis raised the possibility of Antley-Bixler syndrome. Steroid profile (for Antley-Bixler syndrome) and genetic testing for craniosynostosis syndromes (including Antley-Bixler syndrome) were negative, as was microarray, so it was concluded that her deformities, including radiohumeral synostosis, were from methotrexate teratogenicity. Clinicians should not mistake fetal methotrexate syndrome with Antley-Bixler syndrome. Caution when administering teratogens to women of child-bearing age and robust contraceptive and family-planning advice are warranted.