The purpose of this study was to establish the range of spleen sizes in tall healthy athletes. Sonographic measurements of spleen size and left renal length were performed on 129 college athletes (82 men, 47 women). Length, width, and thickness of the spleen and left renal length were obtained. In addition, the height, weight, and age of each athlete were recorded. Pearson's product moment correlation coefficients were calculated, and linear regression analysis was used to create a model for calculating normative values. The mean body height for men was 74.3 (189 cm) +/-(SD) 3.7 inches (9 cm) and for women was 69.3 (176 cm) +/- 3.7 inches (9 cm). Spleen length was greater than 12 cm in 31.7% of the men (mean spleen length, 11.4 +/- 1.7 cm) and in 12.8% of the women (mean spleen length, 10.3 +/- 1.3 cm). In women, height correlated with spleen length (r = 0.3, p = 0.05), width (r = 0.4, p = 0.01), and volume (r = 0.3, p = 0.02) but not with thickness (r = 0.08, p = 0.6). Spleen length did correlate with left renal length (r = 0.5, p = 0.0005). In men, height correlated with spleen length (r = 0.4, p = 0.0003), width (r = 0.5, p = 0.0001), and volume (r = 0.4, p = 0.0002) and less with thickness (r = 0.3, p = 0.01). Spleen length and left renal length were poorly correlated (r = 0.2, p = 0.04). Regression analysis showed that in women taller than 5 ft 6 inches (168 cm), the mean splenic length of 10 cm increased by 0.1 cm for each 1-inch incremental increase in height. In men taller than 6 ft (180 cm), the mean splenic length of 11 cm increased by 0.2 cm for each 1-inch incremental increase in height. Spleen size correlates with height in tall healthy athletes. Nomograms from this data can be used to gauge the risk of returning to play after episodes of acute splenomegaly, as with infectious mononucleosis.