Several autoantibodies were detected in childhood diabetics who were type 1 diabetics, Rheumatoid factor (RF) was studied in tnese diabetics, in normal children and in one adult population. The incidence of RF in 104 type 1 diabetics was 1.9% and that in 473 normal children was 0.6%. The incidence in childhood diabetics was higher than that in control children; however, there was no statistical significance, In 1,229 adult persons, the incidence of RF was 3.8%. 21/567 male subjects (3.7%) and 26/662 female subjects (3.9%) were positive for RF. In the population survey, the incidence of RF gradually increased with aging after the age of 50. Thyroid microsomal antibodies, pancreatic islet cell antibodies and antinuclear antibodies were studied in childhood diabetics and in normal children. The incidence of these three autoantibodies in 104 childhood diabetics was significantly higher than that in the control children.