Aims: The aim of this study is to determine the effectiveness of mandibular infiltration compared with the mandibular block in treating mandibular primary molars in children and to relate it to the type of treatment performed. Materials and Methods: The study design was case control study. The study sample consisted of 98 cooperative children of age 3-9 years old. Forty eight children were the study group (infiltration group). Equal number of children to the study group matched for age and gender were chosen (block group), they had the same criteria of the study group and required the same type of treatment. Dental procedure included amalgam restorations, foromcresol pulpotomies, and extractions. Evaluations of pain for each anesthesia technique and type of treatment were conducted using sounds; motor and ocular changes indicating pain. Evaluations were made upon probing, during tooth preparation, coronal pulp removal and extraction. Results: No statistically significant difference was found between the two anesthetic techniques of pain, when performing amalgam restorations (p>0.05). Mandibular infiltration was significantly less effective than mandibular block for pulpotomy and extraction (p<0.05). Conclusions: In this study, the mandibular infiltration was found to be a reliable local anesthetic technique in amalgam restoration. For pulpotomy and extraction, mandibular infiltration was not as effective as mandibular block. It is recommended to avoid the mandibular infiltration anesthesia, whenever possible for pulpotomy or extraction procedure in primary molars.