This article reports the efficacy of percutaneous autologous leukocyte- and platelet-rich plasma (L-PRP) injection into delayed union site as a minimally invasive method alternative to bone marrow aspirate and open grafting techniques. Each of 15 participants was followed on a regular basis with clinical examinations, roentgenograms. The average time to union was 8.4 weeks after L-PRP injection and the union was achieved in all cases. CD34+/45+ cells counts were increased by 410% and CD34+/45- cells counts were increased by 488% on average in L-PRP. Our investigation showed that L-PRP enrich in stem cells can produce the desired stimulatory response despite a substantial amount of vital bone cells from mesenchymal line. We believe that the using of L-PRP enriched in stem cells, growth factors and antimicrobial proteins might be a promising treatment method in regenerative medicine.