Some blood orange juice (BOJ) flavanones may have antioxidant, anti-inflammatory, anti-allergic, hypolipidaemic, vasoprotective and anticarcinogenic properties. The aim of the present study was to evaluate the pharmacokinetics of hesperetin and naringenin in human subjects after BOJ intake. In a cross-over study, seven healthy female volunteers consumed 150 and 300 ml BOJ corresponding to about 51-102 mg hesperetin and to 6-12 mg naringenin, respectively. Plasma samples were collected before, each hour for 8 h and 24 h after BOJ administration and analysed for their content of hesperetin and naringenin by liquid chromatography-MS/MS. The plasma concentrations of these compounds were dose dependent and the peak concentration (Cmax) was reached in 5.1 (sd 0.6) h after BOJ intake. The Cmax of hesperetin was 43.4 (sd 32.4) and 79.8 (sd 60.1) ng/ml after 150 and 300 ml intake, respectively. For naringenin the plasma peak was 16.4 (sd 11.9) and 34.0 (sd 20.6) ng/ml. Moreover, the conjugated forms of these flavanones represent more than 95 % of the plasma concentration. The results indicate that both hesperetin and naringenin are bioavailable after BOJ intake; naringenin seemingly more so than hesperetin.