Background:Fast and simple pulpectomy procedure is the most optimum goal to achieve while treating a child dental patient. Invention of Ni-Ti led to introducing rotary and reciprocating instruments that aimed to reduce time and procedures during the treatment. Aim of the study: To evaluate the time and cleaning efficacy of single file Reciprocating system (WaveOne, Dentsply Maillefer ) vs. rotary (ProTaper Next, Dentsply Maillefer) and manual K-files in root canal preparation of primary teeth in vitro. Materials and method: A total of 68 extracted human primary molars teeth were collected from the outpatient dental clinics. The Inclusion criteria were teeth with no external or internal pathological root resorption, absence of perforation in the internal or external furcation area, moderate root angulations and more than the two-thirds of the root is intact. Reason for extraction was not related to the study purpose. Standard access cavities were made and the teeth were injected with Indian ink until the ink was visible through the apical foramina. Teeth were randomly divided into 3 working groups (20 teeth each) according to the root canal instrumentation technique (Reciprocating, rotary and manual) and a control group of 8 teeth. Each  theinspectionionionresidual ink were  and forfor 68 extracted human primary molars were collect from the outpatient clinics. Reason for extraction was not related to the study purpose. Inclusion criteria were teeth with no external or internal pathological root resorption, absence of perforation in the internal or external furcation area, moderate root angulations and two-thirds of intact root. A stander access cavities were made and the teeth were injected with Indian ink until the ink was visible through the apical foramina. Teeth were randomly divided into 3 working group 20 teeth each and a control group of 8 teeth. Each group was instrumented according to the manufacturer instruction. Time of instrumentation was recorded for each tooth. After instrumentation teeth were cleared for residual ink inspection and scoring following decalcification, dehydration and clearing protocol. Results:Regarding time of instrumentation, there was no significant difference between reciprocating and rotary groups, while there was a significant time difference between both and the manual group (p < /em> ≤ 0.01). The mean instrumentation times were; 81, 88 and 326 seconds for reciprocating, rotary and manual files respectively. In respect to the cleaning efficacy, there was no significant difference between the two engine driven instrumentation but the difference was significant between each of them and the manual group (p < /em> ≤ 0.01). Conclusion:Using engine driven instrumentation for pulpectomy of primary molars is faster than manual filing during pulpectomy procedures. The single file reciprocating system was a little faster than the rotary files and both were much faster than the manual filling. Engine driven file systems were comparable to each other in cleaning the radicular pulp and yielded superior results in comparison to manual instruments. No file system showed complete cleaning of the radicular pulp. Key words: Pulpectomy, Primary teeth, Single file reciprocating system, WaveOne, ProTaper Next, K-file, Indian ink.