L-arginine and L-lysine are essential amino acids which seem to possess some properties able to influence bone fractures healing. In fact, they seem to be involved not only in the increase of intestinal calcium adsorption but also in collagen synthesis, in insulin and growth hormone secretion and in osteoblastic activation. So, an experimental in vivo model was carried out by using 50 adult rabbits which, under general anaesthesia, were submitted to an osteotomy of the left fibula. Animals were divided into 5 groups and were daily treated with a mixture of lactose, L-arginine and L-lysine or with the only lactose (control group) at the same dosage as recommended for humans. They were sacrificed after 15, 30, 40, 50 and 60 days for radiological and histological studies. The results of the study showed that the pharmacological mixture containing L-arginine and L-lysine accelerates and ameliorates the healing processes and this positive effect was particularly evident from the 30th day after the osteotomy. We think that these results are linked not only to calcium metabolism but also to different biological properties which positively contribute to a good healing of bone fractures.