-Submerged cultivation of Saccharopolyspora erythraea, at different initial spore concentrations, was carried out to study the inter-relationship between inoculum concentration, morphology, rheology and erythromycin production. Pellet morphology was dominant in runs at 10 3 and 10 4 spore/ml initial spore concentrations, whereas there was a significant presence of clump morphology in runs at initial spore concentrations of 10 5 -10 7 spore/ml. The S. erythraea cultivation broths exhibited Newtonian rheology in runs at initial spore concentrations of 10 3 and 10 4 spore/ml, whereas at higher initial spore concentrations the rheological data could be fitted with the power law model. Runs in which clump morphology was predominant resulted in the highest erythromycin productivities. The findings of the present work suggest that the predominance of clump morphology, smaller sized clumps and, in the case of non-Newtonian S. erythraea cultivation broths, a decrease in viscosity enhance erythromycin production.