Nitrogen (N) and mepiquat chloride (MC) affect growth and modify plant architecture, and could alter cotton lint yield and quality. Field experiments were conducted on the North Farm of Mississippi State University during summer of 2001 and 2002 to determine the interactive effects of N and MC on growth, lint yield and fiber properties of cotton cultivar DP 1218B/R. The experiments were arranged in a split-plot design with four replications and consisted of four N treatments of 0, 56, 112, and 168 (control) kg N ha^-1 and four levels of MC of 0 (control), 0.59, 1.17, and 2.34 L MC ha^-1. Plants were harvested three times (square, first flower and boll opening stages) for growth analysis. Pigments and carotenoids concentrations were also estimated. Final seedcotton and lint yield were collected from four rows per plot. Fiber from the various treatments was classified based on Uster High Volume Instrument (HVI) systems. No significant effect of N x MC interaction was observed for the measured parameters. Pigments and carotenoids increased with increase in N and MC levels. Yield and fiber quality parameters were higher in 2004 than in 2003. Increase in N increased growth parameters such as plant height, leaf area, seedcotton and lint yield. In general, 168 (control) kg N ha^-1 resulted in highest lint yield and there was no difference between MC levels for lint yield. In contrast, MC treatments did not alter seed cotton and lint yields. Both N and MC levels had no effect on fiber micronaire. Increase in N increased staple length, fiber uniformity and fiber strength. The increase in MC level increased only fiber length and uniformity. The MC levels tested in this study were neutral in their interaction with N levels as MC levels did significantly alter the leaf area and weight, and final biomass.