A mark-recapture experiment was conducted on Arctic grayling Thymallus arcticus in Piledriver Slough, near Fairbanks, Alaska during 1994. A weir was used to characterize immigration and capture fish for mark-recapture sampling. The weir was fished over a 51 day period beginning in mid-April. A total of 933 Arctic grayling were passed upstream, and 447 fish passed downstream following the mark-recapture experiment. The upstream weir catches were used as the marking sample while catches from a single downstream pass by an electrofishing crew were used as the recapture sample. An estimated 11,747 (SE = 1,297) Arctic grayling > 150 millimeters fork length were present during the early May spawning period. Use of the weir indicated that closure existed for mark-recapture sampling, as very few fish relative to the population size immigrated after the marking event, and few fish had emigrated by the 2 June completion of the weir project. The 1994 stock was characterized by a higher proportion of legal-sized Arctic grayling ( 270 millimeter fork length) than that estimated in 1993, and the age composition was predominated by age 4 fish. The estimated survival was 64%, which indicated more of the stock survived natural and fishery losses in 1993 than in past Piledriver Slough assessments. Restrictions to a no-harvest regulation in 1993 led to lower estimates of exploitation, but estimates of potential exploitation resulting from high catch rates and hooking injury, indicate exploitation rates may still be high.