Studies of urinary mucoproteins were carried out in newborn and infants of hyper-(village) and hypo-endemic (city) areas in North-east Thailand. The findings are as follows: (1) Village newborn excreted significantly higher amount of total non-dialyzable solid (TNDS) than the city group who excreted comparable to the North American newborn. (2) Village newborn and infants excreted significantly lower percentages of 1,000 to 5,000 MW and higher of the above 5,000 MW fraction. At the present time, the reason for the difference and the significance of these finding are not known.