Naringin is the major constituent of grapefruit juice and it is suspected to be one of the causative agents for grapefruit juice-drug interaction. Decoctions of Citri Aurantii Fructus (zhiqiao) and Citri Grandis Pericarpium (huajuhong) whose origins are of the same genus as grapefruit are rich in naringin contents. The aim of this study was to compare the flavanone absorption of grapefruit juice with these two herbal decoctions in healthy Chinese. Six healthy volunteers were given 1000 mL of grapefruit juice and urine was collected for 36 hr. After hydrolysis with β-glucuronidase/sulfatase, naringenin in urine was assayed by HPLC method. By comparing the flavanone absorption of grapefruit juice with those of herbal decoctions obtained in our previous studies, the results indicated that flavaone absorptions of these herbal decoctios are faster in rate, higher in extent and also higher in absorption percention percentage than that of grapefruit juice. If the metabolite of naringin or narirutin is indeed the causative agent for drug interactions, then the coadministration of these herbal decoctions with other western western medicines should be with caution.