This article is from the ER FAQ, by Rose Cooper email@example.com with numerous contributions by others.
One of "ER"`s writer/producers, John Wells, served a similar
function on ABC`s critically-acclaimed Vietnam drama "China Beach".
He reportedly brought some of his old "China Beach" staff members
with him to "ER".
Two actresses from that show have also made appearances on
"ER". Marg Helgenberger, who played K.C. Koloski on "China Beach",
has a recurring "ER" role as Karen Hines, Doug`s former love
interest. Megan Gallagher, otherwise known as Wayloo Marie Holmes on
"China Beach", has also appeared a couple of times on "ER" as Kathy
Snyder, the hospital`s legal counsel. (Some speculated that Kathy
was a potential romantic match-up for Mark Greene when the two bumped
into each other at a singles bar.)
Christine Elise, who played med student Harper Tracy in
"ER"`s second season, also appeared on China Beach, coincidentally
playing the grown daughter of Marg Helgenberger`s character; like
Marg`s "ER" character, Christine`s China Beach character was named
Several other China Beach supporting characters have shown
their faces on "ER", including Colleen Flynn (Colleen Richard), who
played Jodi O`Brian in "Love Labor`s Lost" , and Brian Wimmer
(Boonie Lanier), who showed up in "Last Call"  as a welder
attracted to Jeanie Boulet.