The list  of addresses will be coming from a datalist  on another
worksheet (but within the same workbook). No fancy SQL database and
just a simple datalist. The datalist has fields or columns
companyname (unique master index field), address, telephone, and
contact person. The list will be presorted and should carry no more
than 300 records.

You are correct that I will have to repopulate the dropdown  list
everytime a key is pressed in that certain input field  (or worksheet
cell). Any ideas on the commands to repopulate and only output the
sorted records?