Annatto seed of the tropical bush Bixa orellana, and its products bixin and norbixin are excellent source of natural edible colours. Process optimization of extraction of crude bixin from annatto seeds by water and mechanical agitation followed by its purification to obtain bixin by solvent extraction has been achieved. The various process parameters optimized during this study are: temperature, water/seed ratio, solvent/crude ratio, number of extractions and time of each extraction. The optimization was carried out by performing different sets of experiments and varying only one parameter, at a time, in each set of experiments. For extraction step, four extractions of one hour each at room temperature with 1:3 seed/water ratio was optimized, as this combination gave maximum yield. Similarly, in case of purification, ten extractions of one hour each and refluxing in 1:20 crude bixin/solvent ratio, yielded maximum percentage of pure bixin with carotenoid percentage of 18.6%.