The Renal Insufficiency and Anticancer Medications (IRMA) study is a French national, observational study which demonstrated the high prevalence of abnormal renal function in a population of 4684 solid tumor patients. Among them, 50-60% had decreased renal function, and 80% were treated with anticancer drugs that either necessitated dosage adjustment in case of renal insufficiency (RI) or were potentially nephrotoxic drugs. Since elderly patients are well-known to have reduced renal function, either due to physiological aging or their disease/medication history, a subgroup analysis of this particular population of patients was performed. In 1553 IRMA patients whose age was > or =65 years, the prevalence of RI was very high in spite of normal serum creatinine values in most cases. Anticancer drugs used may be nephrotoxic or need dosage adjustment in a high number of cases.