Nerve injury can arise as a complication peripheral nerve block anesthesia. Of the various factors involved, the trauma caused by the injection needle may be of significance. In this experimental study the frequency of fascicular injury was investigated immediately after needling isolated rabbit sciatic nerve preparations, and after intraneural injection with the nerve in situ. Two different injection needles were used, one with a bevel angle of 14 degrees and the other with a 45 degrees bevel angle. Fascicular injury was indicated by a fluorescence microscopy technique, tracing locally applied Evans Blue Albumin, The results show that a 45 degrees-beveled needle less frequently produces fascicular damage and should therefore be recommended for use in clinical anesthesia. It is also concluded that paresthesiae, when necessary, should be elicited gently, and that intraneural injections should be avoided.