Actual and known mortality· (25 per cent) were thought to be about the same. Eight of the deer hit but not captured were already marked and subsequently observed in good health. Seven others, observed for 10 minutes after being hit, appeared not to be affected and probably did not become immobile. All deaths, except one caused by a BB going astray, were caused by overdoses of drugs. Over estimation of weights of yearlings caused most overdoses. Miller (1968) reported a 10 per cent mortality from the use of succinylcholine chloride on black-tailed deer (0. h. columbianus).Time from injection to collapse was determined for nine deer and averaged 6.4 (2.5 to 10) minutes (Table 1). Two deer, whose immobilization times were 16.5 and 20 minutes, received light dosages (0.07 and 0.08 milligrams per pound) and were not averaged. Miller (1~68) reported an average of 5.9 minutes to immobilize free-ranging black-tailed deer._Only one deer, a yearling buck, was shot with a combination of drugs that did not include succinylcholine chloride. This animal was shot with 5.2 milligrams of M99 and 7.0 milligrams of MTZ, and almost 2 hours were needed to restrain him after injection.Results of this and other tests that included M 99 suggest that Moo may not be effective when injected in a small volume. Although delivery of drugs by the BB cap technique is feasible, the high associated mortality, the difficulty of finding injected deer because of slow drug action, and absence of an .excitement period before immobilization make the use of succinylcholine chloride