Abstract: Melamine （ MA ） is a stable chemical, inactive in vivo metabolism; expelled out body though urine with original molecule form or its analogs. F344 rat＇s plasma elimination half-life 2.7 h, and renal clearance was 2.5 mL/min. MA categorized into low-toxic or non- toxic according to international chemical acute toxicity classification, for its LD50 is 4 550 mg/（kg-bw） in mice. No irritation to eyes of rabbits, guinea pigs and people. Toxicity of MA can be enhanced while accompanied with eyanuric acid for crystal can be formed, and kidney and bladder are targets. Few literatures were found on MA carcinogenicity studies, and the results were inconsistent. IARC says MA is a possible carcinogen for animals, while no evidence was found that MA is carcinogen to human beings. In general, MA is low potential risk material to environment and people.