BLAST tools are typically used to make comparisons between sequences of DNA, RNA and proteins. However, given the exponential growth of the biological databases, there is concern about the performance of BLAST, even considering the equipment of large computing power that exists today. Considering this fact, some tools to run BLAST in distributed environments such as clusters and grids, have been developed to greatly accelerate its performance. However, until now, has not been found in existing literature, no study in order to compare the performance between these tools. The performance evaluation of these tools is usually done in isolation, considering only the execution time (elapsed time) in different situations, for example, varying the number of nodes in the tool BLAST runs. Craving a more detailed investigation, especially with regard to performance evalution of BLAST in distributed environments, this dissertation has as one of your goals make a detailed study to compare the performance of BLAST in a distributed enviroment, considering for such the evaluation of three tools BLAST, among them the balaBLAST developed in the Bioinformatics Laboratory of PUC-Rio. The second objective is to verify the effectiveness of load balancing performed by the tool balaBLAST.