The tissue binding properties of streptococcal lipoteichoic acid (LTA) were studied using normal and passively immunized BALB/c mice. After intraperitoneal injection in non-immunized mice, 3H-LTA concentrations in blood, heart, kidney and liver were highest between 24 and 30 h post-injection. LTA deposits in heart remained high for the next 24 h, whereas other tissue levels decreased. Constant amounts of 3H-LTA were detected in urine throughout the 48 h period. In passively immunized mice, the amount of tissue deposition of 3H-LTA was inversely proportional to the ratio of antibodies to LTA. Autoradiography revealed focal deposits of 3H-LTA in heart, kidney and liver. These observations indicate that LTA, released by streptococci growing at remote body sites, can be carried by the blood to internal organs where it can accumulate and participate in pathogenesis.