Rooting of shoots from in vitro culture of most conifers can be difficult. An antigibberellin, ancymidol, has been shown to promote rooting of in vitro proliferated shoots of asparagus clones, but it has not been tested on conifers. Ancymidol and flurprimidol was tested for rooting on established cultures of Lake States white pine (Pinus strobus). Pulse treatments containing 5 uM ancymidol and 0.5 uM NAA gave 43% rooting, while pulse treatment with 0.5 uM NAA resulted in 7% root formation. Flurprimidol also stimulated root formation on white pine shoots, but was less than ancymidol. Thuja occidentalis `Hetz's Wintergreen' formed roots on 87% of in vitro proliferated shoots when given a pulse treatment with 5 uM ancymidol and 50 uM NAA. Shoots initiated an average of 10 roots after 60 days on vermiculite containing 1/2 liquid MCM medium.