The aim of this study is to establish a rapid and sensitive method for detecting lentinan (LNT) in biosamples and to evaluate the pharmacokinetics of LNT in mice and rats. A diethylenetriaminepentaacetic acid (DTPA) derivative of LNT (DTPA-LNT) was synthesized first to allow labelling with 99m-technetium (99mTc). After purification and identification, 99mTc-DTPA-LNT was intravenously administered to mice (2 mg kg-1) and rats at different doses (0.5, 2 and 8 mg kg-1). The results showed that the 99mTc-labelling method was suitable for the quantification of the LNT concentration in biological samples, with satisfactory linearity (r2 > 0.998), precision (<7%), accuracy (95.01-104.51%) and total recovery (∼90%). The blood concentration-time profiles of 99mTc-DTPA-LNT were consistent with the two-compartment model and showed a rapid distribution phase and a slow elimination, and no significant difference in the blood level of LNT was found among the tested doses (0.5, 2 and 8 mg kg-1). LNT was predominantly incorporated into the liver and spleen, and there was a small amount of aggregation in the bile, kidneys, lungs and stomach. Approximately 40% of the administered radioactivity was detected in urine and faeces within 24 h post-dosing. In addition, SPECT imaging of 99mTc-DTPA-LNT was performed to visually reveal the pharmacokinetic characteristics of LNT. These findings provide a reference for further study and for use of LNT and other β-glucans.