Potential benefit of the topical anesthetic EMLA prior to lumbar puncture was studied in children with cancer. Comparison was made between 2 types of study: the first one involved 10 children who were enrolled in a double-blind placebo-controlled study and in the second, 18 children in an open crossover study. Although both studies suggested the favourable effects of EMLA in alleviating pain associated with LP, they illustrated the need to perform such studies in a controlled blinded fashion; the effect in the double-blind study was not apparent in some cases, whereas it was clear cut in all open cases.