System for monitoring flows of people comprising: - at least one receiving unit provided with at least one antenna adapted to receiving identification data transmitted on a wireless network by mobile communication devices present in a monitored area in which the antenna is positioned, said receiving unit being also provided with a device for processing data collected by said antenna; - a statistical data processing unit programmed to perform statistical processing of the data collected by said antenna and processed by the respective processing device; - a data transmission network which connects the at least one receiving unit with said statistical data processing unit; wherein - the processing device which receives the data collected by the antenna is programmed to perform an anonymization process with compression of the data, such that the data transmitted on the data transmission network are data that cannot be related back to the individual mobile devices that have generated them; - the identification data received by the antennas are MAC addresses of said mobile communication devices; - the device is programmed to process each MAC according to a sequence of processing phases, which involves: I. a first hashing phase with the addition of a cryptographic key identical for all the receiving units and secret. II. a second hashing phase with the addition of a pseudorandom unique cryptographic key. III. a phase of compression and grouping of the results produced by said two hashing phases (H1, H2), so that the space of the possible results of phase II is aggregated producing a space several orders of magnitude lower than the starting MAC address, and producing an aggregate data output or token, such that there is never a one-to-one correspondence between each starting MAC and the token generated by it, and on the contrary, a token corresponds to a group of possible MAC addresses. IV. transmission of the aggregated data produced by the compression and grouping phase, through the network of connection to the statistical data processing unit. - at least one receiving unit provided with at least one antenna adapted to receiving identification data transmitted on a wireless network by mobile communication devices present in a monitored area in which the antenna is positioned, said receiving unit being also provided with a device for processing data collected by said antenna; - a statistical data processing unit programmed to perform statistical processing of the data collected by said antenna and processed by the respective processing device; - a data transmission network which connects the at least one receiving unit with said statistical data processing unit; - the processing device which receives the data collected by the antenna is programmed to perform an anonymization process with compression of the data, such that the data transmitted on the data transmission network are data that cannot be related back to the individual mobile devices that have generated them; - the identification data received by the antennas are MAC addresses of said mobile communication devices; - the device is programmed to process each MAC according to a sequence of processing phases, which involves: I. a first hashing phase with the addition of a cryptographic key identical for all the receiving units and secret. II. a second hashing phase with the addition of a pseudorandom unique cryptographic key. III. a phase of compression and grouping of the results produced by said two hashing phases (H1, H2), so that the space of the possible results of phase II is aggregated producing a space several orders of magnitude lower than the starting MAC address, and producing an aggregate data output or token, such that there is never a one-to-one correspondence between each starting MAC and the token generated by it, and on the contrary, a token corresponds to a group of possible MAC addresses. IV. transmission of the aggregated data produced by the compression and grouping phase, through the network of connection to the statistical data processing unit. I. a first hashing phase with the addition of a cryptographic key identical for all the receiving units and secret. II. a second hashing phase with the addition of a pseudorandom unique cryptographic key. III. a phase of compression and grouping of the results produced by said two hashing phases (H1, H2), so that the space of the possible results of phase II is aggregated producing a space several orders of magnitude lower than the starting MAC address, and producing an aggregate data output or token, such that there is never a one-to-one correspondence between each starting MAC and the token generated by it, and on the contrary, a token corresponds to a group of possible MAC addresses. IV. transmission of the aggregated data produced by the compression and grouping phase, through the network of connection to the statistical data processing unit.