Minimally invasive surgery has become a trend over the last few years in all aspects of orthopaedic surgery, including total hip arthroplasty. So-called mini-incision techniques involve limiting the length of the skin incision to 10 cm with use of either an anterior, lateral or posterior approach. Between March 2004 and December 2005 one hundred consecutive unilateral total hip replacements were performed by the same senior surgeon in our institute. All patients were randomly assigned to study group (group A) or control group (group B). In group A (50 patients) the skin incision was 8 cm; in group B (50 patients) the skin incision was standard (about 12-14 cm). Patient demographic data, including sex, age, height, weight, BMI, diagnosis and preoperative Harris hip score were recorded. Other criteria evaluated included the perioperative and postoperative complications, the surgical time, the blood loss, the length of the incision, the acetabular and stem positions, the length of hospital stay, Harris Hip Score (HHS) and the WOMAC osteoarthritis index at six months. No significant differences were found between the groups with respect to the average surgical time, the acetabular and stem position, the length of hospital stay and the Harris Hip Score (HHS) and the WOMAC osteoarthritis index at six months. A significant lower blood loss was found in the mini-incision group. A higher percentage of peri-operative complications was recorded in Group A (two stupor of sciatic nerve and one fracture of the greater trochanter). On the basis of our experience we could speculate that minimally invasive surgery should be directed to the new surgical approach with muscle sparing, instead of a shorter skin incision using standard approaches.