Seasonal and diel drift of fish were studied in the fifth order of the Illinois River, Arkansas during 1980–1982 to assess the inclination of the various species (ca. 60) in the community (and size groups within species) to drift and to determine their diel and seasonal periodicities of drift. Eighteen taxa were identified from the drift. Channel catfish (Ictalurus punctatus) and flathead catfish (Pylodictus olivaris) alevins represented 57% and 12% of the drift respectively. Slender madtom catfish (Noturus exilis) were abundant in the riffle studied but none were collected in the drift. Larval fish drifted from late April through late August with a peak on 23–24 June when an estimated 37,203 drifted through the study area. A distinct diel pattern was observed with peaks at 2300 and 0300 hours. Drifting larvae were more abundant near the surface and margins with catfish alevins on the deep side and cyprinids, sunfishes, and all prolarvae on the shallow side of the stream. Post-larval development (absorption of yolk sacs) had been attained by 91% of the fish captured in drift nets. This study did not support the idea that all lotic organisms drift at some time during their life history since several species which were abundant or common in the reach were absent or rare in the drift.