  The Milagro gamma-ray observatory employs a water Cherenkov detector to
observe extensive air showers produced by high energy particles interacting in
the Earth's atmosphere. Milagro has a wide field of view and high duty cycle,
monitoring the northern sky almost continuously in the 100 GeV to 100 TeV
energy range. Milagro is, thus, uniquely capable of searching for very
high-energy emission from gamma-ray bursts (GRBs) during the prompt emission
phase. Detection of >100 GeV counterparts would place powerful constraints on
GRB mechanisms. Twenty-five satellite-triggered GRBs occurred within the field
of view of Milagro between January 2000 and December 2001. We have searched for
counterparts to these GRBs and found no significant emission from any of the
burst positions. Due to the absorption of high-energy gamma rays by the
extragalactic background light, detections are only expected to be possible for
redshifts less than ~0.5. Three of the GRBs studied have measured redshifts.
GRB 010921 has a redshift low enough (0.45) to allow an upper limit on the
fluence to place an observational constraint on potential GRB models.
