Simple and sensitive spectrofluorometric and HPLC methods for the determination of ribavirin (RIB) were developed. The methods were based on the reaction of the 5'-hydroxyl group of the sugar moiety in RIB with dansyl chloride in a bicarbonate solution (pH 10.5) to form a fluorescent derivative. The first method was based on measuring the fluorescence intensity of the derivative in dichloromethane at 529 nm (excitation at 382 nm). The second method was HPLC separation of the derivative on a reversed-phase C-18 column with fluorescence detection. The linear ranges were 200 - 900 and 50 - 1000 ng/mL for the spectrofluorometric and HPLC methods, respectively. The derivatization product was characterized by spectroscopic methods. The proposed methods were successfully applied to analysis of the capsules.