Six hundred and six clinical records of patients who were admitted to the Department of Orthopaedic Surgery, Suwa Red Cross Hospital, Nagano, Japan, due to lumbar disc herniation (LDH) between 1991 and 2002 were reviewed to determine the ideal conservative treatment period in relation to different types of LDH: contained and non-contained. Since 1997, we have prolonged in-hospital conservative treatment over a few weeks, which resulted in a decrease in the number of surgeries for non-contained LDH, especially of surgeries performed within 1 month. The number of surgeries for contained LDH did not decrease. The preoperative period of non-contained LDH was significantly shorter than that of contained LDH. These results indicate that for patients who have non-contained LDH, intensive conservative treatment may avoid a surgical procedure. For those patients who have contained LDH, conservative treatment should not be prolonged. We believe that the optimal duration of intensive conservative therapy should be less than 1 month.