The effect of intercropping on stem anatomy of both supporting (Lupinus albus) and supported (Vicia narbonnensis and V. sativa) annual forage legumes was investigated using stereological method. Intercropped plants showed minimal differences in volume densities (Vv) of stem tissues and forage chemical composition compared to sole crops. The proportions of lignin and NDF (Neutral Detergent Fiber) positively correlated with xylem Vv. The proportions of ADF (Acid Detergent Fiber), cellulose and ash in intercropped plants were increased or decreased mostly by less than 10% compared to those in pure stands. The Anatomical Equivalent Ratio (AER) defined as the ratio based on anatomical quality-determining parameters, can assist in the evaluation of the benefits of specific intercropping systems. Intercropping of the legume species studied in this work, especially L. albus with V. sativa, showed encouraging results from anatomical perspective since it would not cause a decline of forage quality.