Contamination of the environment with fibres and fibre fragments is a serious concern facing the textile industry. We studied the comparative marine biodegradation of three wool types and four synthetic fibres with which wool competes commercially, via a method based on a standard biodegradability test. We confirmed that wool readily biodegrades in sea water, consistent with earlier findings relating to soil biodegradation. Wool biodegradation appears to progress through phases relating to its composition and microstructure. We are now investigating the effect of standard chemical finishes used on wool fabrics, and the correlation between accelerated laboratory methods and ‘real world’ biodegradation.