This is a 2 years follow-up study of seventeen women who were found to have mild goiter and post-partum thyroid disease two years earlier in order to establish if post-partum thyroid disease is a self-limited entity or the relapse of a chronic pre-existing disease. When first studied, the 17 women had thyroid dysfunction (15 with hypertyroidism and 2 with hypothyroidism). Eight women had also elevated antimicrosomal antibodies (AMA) titers and 9 were negative for AMA. In the present study, all women were reexamined for the presence of goiter, and free thyroxine index (FT4I), TSH and AMA were determined. Mild (grade I-II, less than 30 g) goiter was found in 11 women. Six out seventeen women, still had altered functional tests (3 with hypothyroidism and 3 with hyperthyroidism). The elevated AMA titers seen in 8 patients in the first study, remained high in 6 (1:100-1:25600). None of the 9 patients who in the first study had negative AMA changed to positive titers. Results indicate that post-partum thyroid disease is not always a self-limited entity. The presence of elevated AMA titers in the initial post-partum period can express a chronic thyroid disease compromise. In these patients a longterm clinical and biochemical follow-up is recommended.