Mixtures of ?-carrageenan-locust bean gum (LBG) were analysed by transmission electron microscopy and dynamic viscoelastic measurements. The effect of two different mannose:galactose (M:G) ratios of LBG on the rheology and microstructure of ?-carrageenan in KCl was studied. The rheological differences observed in the mixed gel as LBGs were added were found to be dependent on M:G ratio, salt concentration and LBG content. Monolayers of dilute samples of ?-carrageenan mixed with LBGs in varying ratios in 0.10 M KCl were visualised by low-angle rotary metal shadowing for transmission electron microscopy. The results obtained showed that LBG hindered the self-association of ?-carrageenan, and that the effect was enhanced at a higher M:G ratio and as the LBG contents were increased. Small deformation viscoelastic measurements were performed on ?-carrageenan-LBG mixtures in 0.050 and 0.10 M KCl at constant temperatures of 38 and 48 °C, respectively. Increased rheological stability was observed for mixtures containing a relatively high LBG content. Mixtures with a relatively low LBG content showed a maximum in storage modulus and an increase in phase angle. The stabilising effect of LBG on the rheology of the blends was more effective for the LBG with high M:G and as the LBG content was increased. © 1996.