OK, Try this

Create a new query "qrydeaccessioned"

Select [accession number], deaccessioned from tbl_journal1 WHERE
deaccessioned is not null

Then change your query to read

SELECT DISTINCTROW tbl_mstr.[accession number], tbl_mstr.Genus,
tbl_mstr.[accessioned date], qrydeaccessioned.deaccessioned FROM tbl_mstr
LEFT
JOIN qrydeaccessioned ON tbl_mstr.[accession number] =
qrydeaccessioned.[accession number]
GROUP BY tbl_mstr.[accession number], tbl_mstr.Genus, tbl_mstr.[accessioned
date], qrydeaccessioned.deaccessioned;


"ChrisJ" wrote:

SELECT DISTINCTROW tbl_mstr.[accession number], tbl_mstr.Genus,
tbl_mstr.[accessioned date], tbl_journal1.deaccessioned FROM tbl_mstr LEFT
JOIN tbl_journal1 ON tbl_mstr.[accession number] = tbl_journal1.[accession
number]
GROUP BY tbl_mstr.[accession number], tbl_mstr.Genus, tbl_mstr.[accessioned
date], tbl_journal1.deaccessioned;


run this query and look at the output
If you are getting lines returned that you don't want, post the line you
want and those you don't describing what makes the lines unwanted.
you may need to go to a union query