Few data are available to help predict which older cancer patient is at risk of developing chemotherapy-related toxicity. This study was a pilot for a project designing a predictive risk score. Chemotherapy patients aged 70 years and older were prospectively enrolled. Chemotherapies were adjusted for their published toxicity. 60 patients were enrolled, 59 were evaluable. Mean dose-intensity was 90.3%, range 33.3-129.0%. 47% of the patients experienced grade 4 haematological and/or grade 3-4 non-haematological toxicity. Published toxicity (MAX2), diastolic blood pressure, marrow invasion and lactate dehydrogenase (LDH) were all associated with toxicity (P<0.1); Body Mass Index, previous chemotherapy, red blood cells, platelets, polymedication with dose-intensity; and polymedication with FACT-G change. After adjustment for the published toxicity, the variables retained their significance, except for LDH and polymedication (for dose-intensity). Although the size of this pilot study imposes a cautious interpretation, patient-related and chemotherapy-related variables correlated independently with toxicity. Designing a composite predictive score to use in assessing the toxicity of multiple chemotherapy regimens therefore appears to be a valid undertaking.