<p>The ²¹⁰Po isotope was used as a tracer to study the transfer of polonium from nutrient solution and soil to lettuce (<i>Lactuca Sativa</i>) grown in hydroponic and soil systems, respectively. The nutrient solution-to-lettuce transfer factors (TF_w) ranged from 1.23 to 5.41 L kg_{fresh weight}⁻¹, with a mean value of 3.01 L kg _{fresh weight}⁻¹. The soil-to-lettuce transfer factors (TF_s) were from 0.32 to 0.65, with a mean value of 0.51. The mean activity concentrations of ²¹⁰Po (AC_Po) in lettuce grown in hydroponic and soil systems were 4.8&#xa0;Bq kg_{fresh weight}⁻¹ and 12.6&#xa0;Bq kg_{fresh weight}⁻¹, respectively. The hydroponic system significantly reduces the AC_Po in lettuce with a significant value (<i>p</i>) of 0.05. The effective dose rate (D_e) was estimated for the normal intake rate of lettuce in Vietnam. The mean D_e values were 3.6&#xa0;μSv y⁻¹ and 9.2&#xa0;μSv y⁻¹ estimated for lettuce grown in hydroponic and soil systems, respectively. The dose assessment shows that the AC_Po in all lettuce samples poses no risk to humans.</p>