Currently hair transplantation is the number one cosmetic surgical procedure in men. American Academy of Cosmetic Surgery (AACS) estimated that there were 177,000 hair transplantation sessions done in the year 2000. As for other cutaneous surgery, various antibiotics are administered during hair transplantation to minimize complications. But the use of prophylactic antibiotics to avoid surgical side infection for clean surgical wounds remains controversial. Although antibiotic prophylaxis can decrease the incidence of surgical side infection, the benefits should be weighed against the risks of toxic and allergic reactions, dysbacteriosis, and the emergence of bacterial resistance. In any case most of surgeons routinely prescribe the use of antibiotics preoperatively (from 1 hour to 2 days before the procedure) and postoperatively (range 5-7 days) for all patients. The objective of this work was the complete clinical observation for surgical side infection risk assessment during large hair transplant sessions which would help us to answer the question: should the antibiotic prophylaxis be used routinely in hair transplant procedures? Three groups of study subjects were defined: first group--100 patients who were operated in our clinic in 2002-2004 years. Number of transplanted FU per session varied between 350-4516 (average 1983+/-4,8). In this group antibiotics were not be administrated. Second group--100 patients who were operated in the same period with 2016+/-47 FU transplantation. In this group all patients received 1,0 gr. ceftriaxone (rocephin, Roche) before surgery and 1,0 gr. ceftriaxone every day after surgery during 5 days. Third group--342 patients who were operated during 1999-2002 years with transplantation of 420-3000 FU (average 1411+/-3,9) per session. In this group all patients received Duracef 500 mg (Bristol Mayers) twice per day after surgery during 1 week. Our observations demonstrated no accidents of surgical side infection or irritation of recipient side or central necrosis in first two groups. 7 cases of SSI and central necrosis were occurred in the third group, but the primary cause of these complications was due to the rough technique in creation of recipient sites (using N16 Nokor needle) or donor closure. Analysis of our clinical observations which has been continued for 6 years and included 542 cases, assures us that prophylactic prescription of antibiotics after hair transplantation is unnecessary especially during strict adherence to the aseptic rules.