Dose-dependent interferonogenic activity and pharmacokinetics of cycloferon--a low-molecular inductor of interferon--have been studied in a group of 35 healthy volunteers. It is established that cycloferon induces the production of early alpha-IFN within 24 h from the moment of drug introduction. In a dose of 500 mg, the drug induces production of gamma-IFN by leukocytes in vitro within 24 h from the moment of introduction, with retention of the titer for 48 h. This proves the need for differentiated approach to a choice of the dose of cycloferon, depending on diseases in which complex treatment involving interferon inductors is required. After the introduction of cycloferon (500 mg) in healthy volunteers, the peak of drug concentration in the blood is observed in 40 min, with the subsequent considerable decrease within 2 h. Variation of the cycloferon concentration in the blood correlates with its content in urine, which is evidence for the drug elimination from organism through kidneys.