The stages by which a pharmacy information system should be implemente
d are described. Implementation cari be divided into three stages. The
first stage is preimplementation, during which the hardware vendor in
stalls and configures the operating system, the software is installed,
the site is prepared, files are built, policies and procedures are mo
dified or written, staff members are trained, functions or programs ar
e tested, and supplies are purchased. The second stage is implementati
on, in which the new system becomes operational and is expanded. There
are four basic implementation strategies: abrupt switchover, parallel
conversion, conversion of one location at a time, and conversion of f
unctions or modules in stages. The final stage is postimplementation,
which consists of testing of the system, acceptance or rejection of th
e system, and the institution of quality control procedures. The accep
tance criteria should be developed before the system is purchased. It
is important to involve the pharmacy staff and other hospital departme
nts in the planning for an information system. Careful management befo
re, during, and after the implementation of a new pharmacy information
system is essential to a smooth and timely conversion.