Liming soils is an important part of the overall fertility program for soybean [Glycine max L. (Merr.)] production. Soybeans are adversely affected by acidity when the pH falls below about pH 5.8. Considerable interest exist is Iowa on soil pH specific management recommendations. Since soil pH varies across Iowa, it is likely that current optimum plant population for soybean need to be optimized depending on soil pH. The objective of this study is to identify the optimum plant population for soybean at different soil pH. Research was conducted in Iowa from 2003 to 2004. The experiment was a randomized complete block in a split plot arrangement with four replications. Main plots were 5 lime treatments (0, 4, 12, 36, and 108 tons aglime hectare^-1) applied in 1995. Soil pH for the different treatments was on average 5.4, 6.0, 6.5, 7.1, and 7.8. Continues corn has been grown in the field since 1995. The sub-plots consisted of 5 seeding rates (180,000, 300,000, 420,000, 540,000, and 660,000 seeds hectare^-1). Seed was inoculated with Bradyrhizobium japonicum (Liphatech, Milwaukee, WI) and each plot (3 m by 11.4 m) was planted in four rows at 76 cm row spacing. No differences were found among lime treatments and soil pH on soybean yield, grain moisture, height, lodging, or grain composition. Grain yield was lowest for the lowest plant population (180,000 seeds hectare^-1). However, no differences were found among the remaining 4 plant populations. Grain moisture and oil content decreased as plant population increased whereas plant height and protein content increased as plant population increased. It was concluded that soil pH did not influence soybean plant population and should not be considered when optimizing the seeding rate.