A block data compression system comprising a Compression unit and a Decompression unit, and an Algorithm for fast block data compression using multi-byte search.Objective of the invention is to develop a block data compression system and algorithm for fast block data compression with multi-byte search for optimal encoding during the learning phase of substitutional methods, allowing length-limited and relative small blocks of input data symbols to be compressed independently, as required by random-access storage or telecommunication devices; and reaching high-performance characteristics by employed accelerating architectures and highly pipelines data-flow principles.According to the present invention these objectives are accomplished by a Compression Unit comprising an Input-FIFO (8), connected to a Modeling Unit (6), where said Modeling Unit (6) is connected to a multitude of memory locations represented by Trie-Dictionary (4) memory, to a Zero-Finder Look-Up Table (3), to search means in the form of a Comparison Unit (5), to memory means in the form of a Literal-Dictionary (2) and also to an Encoder Unit (7); said Encoder Unit (7) also connected through an Aligning Unit (7) to an Output-FIFO (12).The invention comprises a block data compression system, composed of a Compression Unit and a Decompression Unit, and an algorithm for fast block data compression using multi-byte search; and is related to the field of data compression, specifically to the implementation of a lossless, adaptive, reversible and fast block data compression for storage and telecommunication devices.