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Scanning and transmission electron microscopy were used to study the progressive disruption of Merino wool during the vigorous agitation of the fibres in aqueous 10J0 (w Iv) solutions of sodium dodecylsulfate (SDS). In contrast to the general disruption observed when wool was vigorously agitated in formic acid, the cuticle was slowly stripped from the fibre with virtually no release of cortical material unless prolonged periods of agitation were used. A similar type of disruption took place in aqueous 10J0 (w Iv) solutions of cetyltrimethylammonium bromide (CETAB) and Triton X-lOO. After the agitation in 10J0 (w/v) SDS solution, the released cuticle fragments and the remaining fibres were examined. Only a minority of the cell portions constituting the cuticle fragments had been cleaved within the endocuticle. Often, the fragments included portions from more than one cuticle cell, with the cell junctions still intact. An understanding of the disruptive process was facilitated by the frequent observation, on residual fibres, of low ridges on exposed underlying cuticle cells. These low ridges corresponded with the distal edges of the originally overlying cuticle cells. Amino-acid analysis and scanning electron microscopy performed on preparations of cuticle obtained in solutions of the above detergents and in formic acid indicated close similarities between all of the cuticle preparations.