The paper put forward a study on the introduction of monoecious hemp into the culture with implications concerning the variation in the THC content in breeding and selection processes. Extension of hemp cultivation is possible only by reducing the cannabinoid content under 0.3% in the European Union and under 0.2% in Romania. The reduction process of the THC content in improving and creating monoecious hemp varieties started by hybridization works, backcrossing, followed by repeated selection and multiplication in isolation conditions. Finally, the monoecious lines led to obtaining Dacia Secuieni varieties, for strains and fiber and Secuieni Jubileu for seed, whose THC content was below the detection limit (0,01%, 0.008% THC content, respectively). It resulted an annual genetic progress of 0.046% between Secuieni 1 variety (the first approved variety with 0,4 - 0,6% THC) and the last approved Secuieni Jubileu variety.