A statis-tical analysis with computer technic was made of 81 cases in which the spleen was visualized on plain films of the chest or abdomen within 8 weeks of death. The vertical length from the tip of the spleen to its intercept with the diaphragm (L) provided the single best statistical estimate of spleen weight. An L of more than 15 cm gives a 98% probability of an enlarged spleen by the pathologist''s criteria. A mathematical formula uses L and the width of the spleen to slightly improve the statistical accuracy in the prediction of spleen weight. The above measurements cannot exclude splenomegaly.