The contribution of Kenai River coho salmon Oncorhynchus kisutch to commercial fishery harvests of Upper Cook Inlet was estimated for the first time in 1993 based on recoveries of adults marked as juveniles with coded wire tags. The drift gill net and the eastside set gill net fisheries of the Central District were examined during the period when 95% and 91% of the respective total harvests occurred. An estimated 1,040 and 6,472 Kenai River coho salmon were harvested in the drift gill net and eastside set gill net fisheries, respectively. These harvests represented 1% of the drift gill net harvest (117,924 coho salmon) and 17% of the set gill net harvest (38,725 coho salmon) during the period sampled. The Kenai River contribution comprised a considerably lower proportion of the total harvest than expected. The majority of the harvest was comprised of stocks of unknown origin. Contribution estimates were stratified by date for both fisheries and additionally by statistical area for the eastside set gill net fishery. No significant trend in contribution was evident in the drift gill net harvest because of the low contribution estimate. Estimated contributions to the eastside set gill net harvest ranged from 0% to 52% among four statistical areas and during four sampled periods. There was an increasing trend in the contribution to the harvest in each statistical area over time. During the sampled period, there was an increasing trend in proportional contribution and a decreasing trend in total harvest from the northernmost statistical area to the southernmost. The most abundant group of marked fish returning to the Kenai River was the cohort marked as smolt at the Moose River in 1992. The proportion of the entire Kenai River return marked at the Moose River was 0.0728. This proportion was estimated by examination of the inriver recreational harvest and served as the basis for estimating contribution to commercial fisheries. The marked proportion remained relatively constant over the duration of the recreational fishery during August and September. This indicates that smolt emigrating from the Moose River are a representative sample of coho salmon from the Kenai River with respect to return timing. The Moose River is therefore a practical site for marking smolt in the future. Based on the marked proportion of 0.0728, the abundance of smolt emigrating from the Kenai River in 1992 was about 1 million. This estimate is biased high due to long-term tag loss. Long-term tag loss for all marked cohorts returning to the Kenai River was estimated as 9%. A total of 61,769 Kenai River coho salmon were harvested in UCI during 1993: 7,512 in commercial fisheries; 52,828 in the Kenai River recreational fishery; and 1,429 in the Kenai River personal use dip net fishery.