To assess the benefit of intraventricular chemotherapy, patients with leptomeningeal metastasis (LM) from breast cancer were randomised to treatment including intraventricular (IT) chemotherapy (n=17) or to non-intrathecal (non-IT) treatment (n=18). Appropriate systemic therapy and involved field radiation therapy (RT) were given in both arms. Intention-to-treat analysis showed neurological improvement or stabilisation in 59% of the IT and in 67% of the non-IT group, with median time to progression of 23 weeks (IT) and 24 weeks (non-IT). Median survival of IT patients was 18.3 weeks and 30.3 weeks for non-IT patients (difference 12.9 weeks; 95% Confidence Interval (CI) -5.5 to +34.3 weeks; P=0.32). Neurological complications of treatment occurred in 47% (IT) vs 6% (non-IT) (P=0.0072). In conclusion, standard systemic chemotherapy with involved field RT for LM from breast cancer is feasible. Addition of intraventricular chemotherapy does not lead to survival benefit or improved neurological response, and is associated with an increased risk of neurotoxicity.