Aims: This invitro study was done to evaluate the chem. and biol. properties of 4 brands of metal orthodontic brackets. Objectives: To analyze the chem. composition, the corrosion resistance, Nickel ion release and cytotoxicity of the orthodontic brackets. Methods: Four brands of orthodontic brackets namely: Group-1: Gemini(3M Unitek), Group-2: Ecoplus(Chirpans Orthodontics), Group-3: Monalisa(JJ Orthodontics), Group-4: Sapphire(Modern Orthodontics). Composition was analyzed by Scanning- electron Microscopy with Energy Dispersive spectroscopy. Corrosion resistance was done by potentiodynamic polarisation in artificial saliva. Nickel ion release from the brackets was analyzed by inductively coupled plasma mass spectrometry, at 24 h, 7, 14, 28 days. Cytotoxicity of the brackets were analyzed by Live- dead assay and MTT assay. Results: Gemini brackets offered better corrosion resistance and showed the least nickel release among all the groups. Cytotoxicity tests showed that Gemini is the least cytotoxic and Ecoplus is the most cytotoxic. Conclusion: The study concluded that Nickel ion is highest in Gemini brackets, but the nickel ion released from Gemini is the least among the four groups and showed better corrosion resistance and least cytotoxic.