This paper reports the preliminary results of a microscopic study carried out on stem cross sections of hemp. Stems were harvested from two field experiments carried out in 2001 and 2002 in the north of Italy to compare the monoecious genotype Futura 75 over four plant populations. Fibre characteristics such as cell shape, diameter, maturation and quantity of secondary fibre tended to vary with harvest time, plant density, and between and with internodes. After the end of internode elongation, fibre cells changed from oblong to round shaped in cross section and fibre maturation started and progressed to a maximum level. At various moments of the growing cycle, fibre maturity and presence of secondary fibre seemed higher at lower internodes and plant density.