Molecular chaperones prevent protein aggregation. Understanding of their mechanism of actions remains obscured by the complexity of their three dimensional structure. Surfactants are much simpler molecules and can also inhibit protein aggregation. In the present work, prevention of aggregation by ionic and non-ionic surfactants during thermal and non-thermal unfolding and refolding of a number of proteins are studied. Attempts have been made to compare the dose dependence of surfactants with that of molecular chaperone a-crystallin in preventing various protein aggregations. Conformational features of proteins whose aggregation have been prevented by surfactants and a-crystallin are compared with each other. It has been found that in terms of conformation of the substrate protein, chaperones restrict the bound protein in a conformation not far from that of the native protein, whereas ionic surfactants may lead to considerably different substrate protein conformation. Non-ionic surfactants, though slow in solubilising protein aggregates, do not cause great changes in protein conformation.