I am creating a database for storing cancer tissue samples. These samples can be from one of 5 sites (colon, breast, prostate, lung, cervical). Based on the location of the tumor, the sample will have a corresponding pathology read under the microscope. For example, if the sample is from the lung, there are certain types of pathology (spindle cell) that apply only to lung samples not to colon samples.

In creating the form, I would like for the data entry person to enter the site of the sample first (one of 5 choices on a drop down list) and then have a query run that will then generate the appropriate drop down list for the pathology field that is specific to the site entered.

I have tried to do this by creating a table with site and pathology in it for all sites and possible pathologies. I then created a form where the site information is entered first and a query is associated with the pathology field. This query, based on the table I created, looks at the site field (only once for multiple records) and does not return the correct drop down list. Can anyone help me out of this jam?

Sounds like you need "cascading combo" boxes. You should do a search of the forums. There are lots of examples. Here's one thread with links:
http://www.access-programmers.co.uk/forums/showthread.php?s=&threadid=49150&highlight=cascading+combo+boxes