To the Editor:—We read with interest Dr. L. N. Nichey's report Thyrotoxicosis in a Mongoloid Child in your May (1960) issue since we recently studied what we believe to be the youngest recorded example of this dual condition (Colver et al., 1958). As Dr. Nichey mentions, these occurrences (he refers to three others) appear to be coincidental but perhaps an open mind should be kept since (a) our patient was only 6 years old and the chances against coincidental occurrence at this age must be very high, (b) we know by the analogy of leukemia and Mongolism (Krivet and Good, 1957) how easily significant associations of this nature are overlooked until relevant surveys are made, and (c) five examples of thyrotoxicosis in Mongolism (four in children) have been published since 1945 and recalling our own hesitancy to record our patient we suspect that the condition is commoner than medical