Abstract: A computer system (11, 12, 13) and method for managing data used in conducting clinical studies concerning subjects at a plurality of participating, geographically distributed clinical sites, each participating clinical site having a computer (17, 18, 19) for inputting, transmitting and receiving data over the Internet (15). An Internet network server computer (13) is interfaced to a database host computer (11) through a private network (12). The system (11, 12, 17, 18, 19) communicates data over the Internet (15, 16) to determine patient eligibility, randomization and initial prescriptions, which can then be adjusted by the physician online. The final prescription is printed out for signature and sent electronically to a distribution center (55). Study data is maintained in a database in the host computer (11) behind a firewall provided in the Internet server computer (13).