Introduction: Metalaxyl is a widely used fungicide, with high residual level in crops that lead to dangerous human health problems. Aim of Work: Study effect of metalaxyl on the thyroid gland structure& function and evaluate the efficacy of ginger supplementation. Materials and Methods: Thirty female albino rats were classified into three equal groups: Group I: (control group): Subdivided into two equal subgroups 1a: given distilled water by gastric tube for 8 weeks. 1b: given ginger (100mg/kg /day) by gastric tube for 8 weeks. Group II: given metalaxyl 3 times per week (130 mg/kg/day) by gastric tube for 8 weeks. Group III: given the same dose of metalaxyl given to group II concomitant with ginger by gastric tube for 8 weeks. At end of the experiment, rats were anaesthetized, and blood samples collected for measurement of T3, T4 and TSH. Thyroid gland biopsies were processed for light and electron microscope examination. Immunohistochemical study was done for detection of PCNA. Results were analyzed morphometrically and statistically. Results: Metalaxyl-treated rats showed numerous interfollicular cells, vacuolated colloid, an increase height of follicular epithelium and many follicles exhibited stratification with vacuolated cytoplasm, dilatations of endoplasmic reticulum and irregular dark nuclei. Positive immunoreaction was detected in numerous nuclei of follicular cells of group II and significant decrease in T3, T4 with highly increase in TSH. Group III showed a considerable degree of improvement of thyroid architecture. Conclusion: Metalaxyl affects the thyroid follicular structure and function. Concomitant administration of ginger was partially efficient in protecting it.