A study, carried out in 100 African patients on intermittent therapy with RMP in high dosage (30 mg/kg) combined with INH or EMB, has shown that high and long-lasting RMP serum levels could be obtained, covering a 24-hour period. The mean RMP peak levels reached 17.7 µg/ml, the mean serum levels after 12 h still 6.4 µg/ml and after 24 h 1.3 µg/ml. No signs of accumulation have been observed after administration of three such high doses on alternate days. On the contrary the 12- and 24-hour serum levels were significantly lower after the second and third drug administration. Patients treated with RMP-INH had somewhat higher RMP serum levels than patients with RMP-E