Ropivacaine is a newly used local anaesthetic in Iran. Replacing this newer developed drug instead of older bupivacaine has many clinically significant benefits. Block failure is reported repeatedly by Iranian anaesthesiologists in spinal anaesthesia by intrathecal ropivacaine. A few theories can explain the reason for higher block failure with intrathecal ropivacaine compared with bupivacaine. Non-commitment to using intravenous sedative medications may be the most justifiable reason for this phenomenon.