Plasma and lung lymph β-glucuronidase and aryl sulfatase A specific activity were measured before and for 48 hours after a 50% full-thickness burn in the adult sheep. We noted a significant increase in plasma activity of both enzymes with maximum increase occurring 3 hours postburn, with levels returning toward baseline at 48 hours. Increase in plasma activity correlated in time course with increases in pulmonary vascular resistance. Lung lymph specific activity increased to levels identical to that in plasma but the time course lagged behind by 1 to 3 hours.