Nickel-Cadmium (Ni-Cd) batteries are secondary rechargeable battery which contain nickel oxyhydroxide as cathode and metallic cadmium as anode. Ni-Cd batteries have different applications in aircraft, electronic flash units, toys, emergency lights, medical instrumentation and cordless applications. These batteries can also be used for over 20 years because of its rechargeable characteristic but after that period of time, large number of Ni-Cd batteries will be discarded into the environment because of the lack of environmental regulations especially in developing countries. The toxic transition elements like Nickel and Cadmium are still retained in the discarded Ni-Cd batteries and this might leach into the groundwater and soil when the outer shell of the battery is broken thus making it unfit for use by humans. The exposure of Nickel and Cadmium in batteries can reach humans through food chain and affect human health adversely. So, more importance should be paid for the treatment of discarded Ni-Cd batteries in order to avoid problems to the environment and its effect on human health. This review discusses the heavy metals in Nickel-Cadmium batteries, Nickel (Ni) and Cadmium (Cd), its effects on environment and humans and then concentrates on methods to restrain them.