SUMMARY:Block anesthesia of maxillary nerve 9BAMN) is achieved by depositing anesthesia through greater palatine canal into the pterygopalatine fossa. Authors differ in the amount of anesthesia to be administered and the rate of complications (diplopia and hematomas), Coronado et al., (2008), measured the size of the pterygopalatine fossa finding an average of 1.2 ml, suggesting that amount of anesthesia for BAMN. The aim of this study is to compare the effectiveness of low doses of 1.2 ml (LD)versus traditional dose of 1.8 m. (TD) of anesthesia for BAMN and its adverse effects. A quasi experimental exploratory clinical study was performed involving 82 patients where the anesthetic technique was suitable for tooth extraction procedure; patients were randomized in LD and TD groups, 2% lidocaine with 1:50.000 epinephrine was used. Demographic (sex and age), clinical (tooth for extraction and anesthetic dose) as well as anatomical variables (upper facial and cranial index) were recorded. The anesthetic success (AS) was defined as the possibility to perform the tooth extraction with no pain or minimal pain as measured by visual analogue scale (VAS). For statistical analysis chisquare and t test (p <0.05) were used. The results show that the pain and AS were 2.93 and 61.67% in LD group and 3.09 and 59.09% in TD group respectively, there were 6 cases of diplopia with no significant statistical difference between groups.