The abundance of coho salmon Oncorhynchus kisutch that returned to the Chilkat River in 1998 was estimated using a mark-recapture experiment. Fish were marked in the lower Chilkat River with individually numbered solid-core spaghetti tags and batch marks. Fish were later sampled upriver near spawning grounds to recover tags and estimate marking fractions. Eight hundred twenty-nine (829) coho salmon 500 mm mid eye to tail fork (MEF) were marked in the lower Chilkat River between August 8 and October 13, 1998 in fish wheels and drift gillnets. We examined 1,526 coho salmon 500 mm MEF on spawning areas of the Chilkat River drainage, and 27 of these were marked. A Darroch estimator was used to estimate that 37,132 (SE = 7,432) coho salmon 500 mm immigrated into the Chilkat River during 1998. We estimated that 72.5% (SE = 2.3%) of these fish were age 1.1 (1995 brood year), and 27.5% age 2.1 (1994 brood year). Most (55.6%, SE = 1.3%) were males.