The reniform nematode and silverleaf whitefly are serious pests to cotton in the Lower Rio Grande Valley (LRGV) of Texas. A 2-yr study, from 1995 to 1996, was conducted to determine the singular and combined effects of reniform nematodes and silverleaf whiteflies on lint yield and fiber quality. Experimental design was a split-plot, with nematode treatments (Telone II and control) as the whole plots and whitefly treatments (imidacloprid and control) as subplots. First harvest yield was significantly reduced by reniform nematodes, but not by whiteflies. Second harvest and total lint yield were reduced by both reniform nematodes and whiteflies. Micronaire value was significantly lower when whiteflies were not controlled, while fiber elongation was lower when reniform nematodes were not controlled. Fiber length and strength did not appear to be affected by reniform nematodes or silverleaf whiteflies. Across years and whitefly treatments, total yield in the Telone II plots was 590 lb/acre compared to 416 lb/acre in the nematode-infested plots. Averaged across nematode treatments, total yield was 565 lb/acre in the imidacloprid plots and 441 lb/acre in the whitefly-infested plots. No highly significant reniform nematode x silverleaf whitefly interactions were detected; however, there was indication of some interaction (P≤0.20) occurring for the second harvest. The results indicated lint yield reductions caused by reniform nematodes and silverleaf whiteflies. Since the later maturing percentage of the crop suffured the most loss, managing for early maturity should be an effective strategy for reducing yield losses caused by these two pests.