E341 (tricalcium phosphate) (TCP) is commonly used as a food additive and also as a nutritional Supplement. To evaluate the possible developmental effects, female Wistar rats were treated with E341 (TCP) by oral gavage during pregnancy. There were three groups of each containing five rats. Rats in Groups I-III were fed with standard diet, oil and E341 (TCP) 175 mg/kg body weight during gestation days (CID 0-20) respectively. We assessed foetal body lengths and weights and also made morphometric examination of placenta and umbilical cord. The placental weights of E341 (TCP) group (Group III) were found to be decreased statistically. According to skeletal stainings of foetuses, lengths of left ulna (28.3%), right femur (29.8%), left femur (34.9%) and diameter of the skull of y-axis were significantly decreased (12.3%) in E341 (TCP) treatment groups. There was an increase in trans-umbilical diameter in treatment group (14%). This is the first study in which developmental effects of E341 (TCP) have ever evaluated. The results suggest that prenatal development of rats during gestation is sensitive to E341 (TCP) exposure. (C) 2009 Elsevier B.V. All rights reserved.