The aim of the study was to determine the effect of boron fertilization on agromorphological properties of berseem (Trifolium alexandrinum L.). The field experiment was arranged in randomized blocks with divided parcels. It was applied with 3 replications in 2017 and 2018 years in Ankara conditions. Three different berseem varieties (Derya, Erix, Mario) were sown to main parcels and 5 different boron fertilizer doses (0, 100, 200, 400, 800 g da-1) were applied to sub-parcels. According to the research results; plant height was varied between 67.20 and 98.33 cm. Stem diameter was 3.43-4.45 mm, stem numbers were 6.17-11.67 pieces and head numbers were 7.28-15.02 pieces. The highest plant height and stem diameter were exhibited by variety of Mario. Erix displayed the highest development in terms of stem numbers, Derya showed the highest development in terms of head numbers. When boron doses were compared with control parcel, the highest plant height, stem diameter, stem numbers and head numbers were obtained at 100 g da-1 boron dose.