A simple, rapid, reliable and sensitive method based on liquid chromatography with fluorescence detection (LC-FL) for the quantification of doxorubicin (DOX) in human plasma and urine samples was developed. The assay was carried out after the solid-phase extraction procedure (SPE) with hydrophilic-lipophilic balance (HLB) cartridges, and with daunorubicin hydrochloride (DAU) used as the internal standard. Chromatographic separation was performed on a Discovery HS C18 column in isocratic elution mode, and the detection of the analytes set at excitation and emission wavelengths of 487 and 555nm, respectively. The developed LC-FL method has been validated for accuracy, precision, selectivity, linearity, recovery and stability. The limits of detection and quantification for DOX were 0.5 and 1ng/mL in both biological fluids, respectively. Linearity was confirmed in the range of 1–1000ng/mL and 0.001–25μg/mL in plasma and urine samples, respectively, with a correlation coefficient greater than 0.9994. The proposed LC-FL method is selective, precise and accurate, and has been successfully applied for drug monitoring in pediatric cancer patients treated with DOX as a component of OEPA (Oncovin (Vincristine)-Etoposide-Prednisone-Adriamycin) and IOA (Ifosfamide-Oncovin-Adriamycin) chemotherapeutic schemes. Moreover, real exposure of hospital personnel to the anthracycline drugs in plasma and urine was evaluated in clinical practice.