Some epiderniologic studies .suggest rwrkers who rotute shqt (ire at incwuserl risk of cardiovnsculrr diwust~, but no .studies have studied the @ect of sh$ f o r rtnrker.s rho do not rotate. To determine whether currelit shift or rtvent cliunge in sliiji IL'NS LZ risk ,fiic.tor ,fiw ischemic heurt tlisease, we conducted u nested c.tisr-cotitro1 study of hlwrt disease decith trt n w k rtithin a colrort of 2 1.000 inen working Lit ,Ji)ur hecry. equipment plants. We idcntqied 163 nieii who died of ischernic heurt disotrst~ nt work or nithin I rt-eek of working, t i n d conipared them to 781 controls who were working ut the .xime age hut did not die. Plrnt l~ersonnel rtw)rcls Itsere used to det(>rmine diirutioii of' tinie on twrrtwt .shift. At fhe tirw of case death, 7 2 8 of sturly su1,ject.s were workiiig o i l ,first shift. 22% on second, und 6% on third. The avercige titne on s h i f t cttithout ,shift chnrige CVNS 9 yeurs. There N X I ~ little eiidence of uny diflerence in herirt diseme risk by current shift. There I Z ~ soine indication thiit recent chunge .froin qfternoon or night shift to diiy shift hiid u protective erect initidly, which decreased over time. On the other liuiid, no iw-rilsponding negotive eflect MYIS ,found jhr N chrrnge ,from jirst to second/thirrl s h jft. regardless o f r t h c ~r i the cliunge took p l o w . Our mu1y.se.v wert liniited bv the srnull number of ktwkers on the third shift. We consider oiir uno1yse.s to be expIoratiw,v, tind tncoiirage inon' riwurc~h on this topic in other n.orking p o p h t i o n s . C; /()Oh IVi/c,-f.i.w. /tic.