Conventional lumbar microdiscectomy requires subperiosteal dissection of the muscular and tendineous insertions from the midline structures. This prospective, randomized, single center trial aimed to compare a blunt splitting transmuscular approach to the interlaminar window with the subperiosteal microsurgical technique. Two experienced surgeons performed first time lumbar microdiscectomy on 125 patients. The type of approach and retractor used was randomized and both patients and evaluator were blinded to it. In 59 patients a speculum-counter-retractor was inserted through a subperiosteal (SP) route and in 66 patients an expandable tubular retractor was introduced via a transmuscular (TM) approach. In both groups the mean age was 51 years, the male gender prevalent (61%) and the distribution of the operated levels was similar. The outcome measures were VAS for back and leg pain, ODI and the postoperative analgesic consumption was scored by the WHO 3-class protocol. A postsurgical VAS (0–1) was defined as excellent, VAS (2–4) as satisfactory result. In this study the patients scored from 1 to 3 points daily according to the class of drugs taken. Furthermore, a 1/3 point (class 1), 2/3 point (class 2) and 1 point (class 3) was added for each on-demand drug intake. Recovery from radicular pain was excellent (SP 68%, TM 76%) or satisfactory (SP 23%, TM 21%). Recovery from back pain was excellent (SP 58%, TM 59%) or satisfactory (SP 37%, TM 37%). Postoperative mean improvement ODI was: SP 29% and TM 31%. Postoperative mean analgesic intake: SP 4.8 points, TM 2.6 points (P = 0.03). Lumbar microdiscectomy improves pain and ODI irrespective of the type of approach and retractor used. However, the postsurgical analgesic consumption is significantly less if a tubular retractor is inserted via a transmuscular approach.