Visual perceptual integrative motor ability was investigated in 719 6- to 12-yr-old, presumably normal, primary schoolchildren living in 2 iodine-deficient endemic goiter areas in Sicily, identified on the basis of the presence (area A) or absence (area B) of endemic cretinism, by administrating the Bender Gestalt test. All of these clinically euthyroid schoolchildren were also examined neurologically by an investigator unaware of the result of the Bender test. Ninety-nine (13.76%) schoolchildren were found to be defective by the Bender test; this prevalence was significantly higher than that (3.0%) found in an iodine-sufficient goiter-free control area (area C) lying at sea level (chi 2 = 36.25; P less than 0.000001). No difference in the prevalence of Bender abnormalities was apparent if the children were divided according to the area of provenience (area A, 14.4%; area B, 13.1%). A high percentage of children falling in the lower range of normality was found in both area A (15.5%) and area B (19.0%); this was significantly higher than that in area C (3.8%; chi 2 = 77.55; P less than 0.000001). Neuromuscular and neurosensorial abnormalities, including increased tendon reflexes, clonus of the foot, Babinski sign, minor disturbances in balance, and gait, and minor defects in hearing and speech, were apparent in 19.3% (area A) and 18.5% (area B) of the children. These disorders were significantly more frequent in defective children identified by the Bender test (33.3%) than in normal children (15.3%; (chi 2 = 17.29; P less than 0.00005). The general intellectual aptitude in Bender deficient subjects was evaluated by the Terman Merrill test and was found to be impaired in 95%, thus confirming the existence of an endemic cognitive deficiency (ECD), distinct from the endemic mental deficiency previously found in other endemic goiter, iodine-deficient areas. ECD seems to be epidemiologically independent of the existence of endemic cretinism. Further clinical auxological and biochemical studies in a selected group of ECD children suggested the epidemiological and, possibly, pathogenic association of cognitive impairment with iodine deficiency.