The effect of short-carbon fibre on the anisotropy in hysteresis loss and tension set of two thermoplastic elastomers, based on natural rubber, high-density polyethylene blend and styrene-isoprene-styrene block copolymer, were studied. The composites based on natural rubber-high density polyethylene blend show anisotropy both in hysteresis loss and tension set, whereas styrene-isoprene-styrene shows lack of anisotropy in both cases. Ah empirical relationship has been established relating (DELTAw)It, (the difference between the hysteresis loss between systems with longitudinal fibre orientation and transverse orientation) and the strain per cent and volume per cent of fibres.