The main task in the drug intolerance reactions is the choice of "alternative" drug by oral challenge. The tolerance of rokitamycine (RKM), a new macrolide with a wide activity spectrum in 133 antibiotic-intolerant patients has been studied by open oral challenge with incremental dosage until a cumulative dose of 406 mg. The RKM in 96.2% of cases has been well tolerated. Only 5 patients (3.8%) have had reactions, mainly "atypical" and of minor clinical importance, at cumulative doses ranging from 31.25 to 250 mg. The RKM has been well tolerated also by 6 patients who have had reactions to macrolides belonging to the same group (16 membered). Finally, the use of RKM as alternative drug in chemotherapeutics-intolerant patients has been proposed.