The present study was an attempt to evaluate the role of ultrasonography on decreasing the number of attempts, failed punctures, time needed to perform the procedure and patients' pain. Methods: This study is a prospective case-control. Patients were divided in two groups randomly. A two-dimensional probe was used to localize intervertebral space in the ultrasound guidance (US group). In manual palpation (MP group) however, insertion level was determined using the standard technique by manual

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... lpation. The number of attempts (needle insertion) required for a successful tap and successful/unsuccessful attempts were considered as the primary outcome measures. Results: Male patients with an average age of 44.08±15.83 years accounted for 60% (30 individuals) of the population. Success rate was 92% in the US group and 34% in the MP group (P<0.001). It took 79.64± 19.91 and 85.4±11.62 minutes to identify the proper location in US and MP groups respectively (P=0.21). In the first attempt, it took 6.33±0.95 and 6.87±0.7 minutes to collect cerebrospinal fluid (CSF) in US and MP groups respectively (P=0.02). Average time taken to localize the sites in two attempts were 8.28±2.44 and 13.17±3.32 in US and MP groups respectively (P<0.001). Average number of attempts made in the US and MP groups were 1.08±0.27 and 1.64±0.66 (P<0.001) respectively. Conclusion: Ultrasonography has reduced the time needed for locating puncture to collect CSF, pain management in patients, determining the number of attempts, and defining the risk of traumatic puncture. Moreover, this technique is characterized by a higher success rate. Using ultrasonography in obese patients and people with lumbar problems is more important.