The toxicity of secondary waste effluents from textile manufacturing plants was determined with freshwater (Selenastrum capricornutum, Daphnia pulex, Pimephales promelus) and estuarine (Skeletonema costatum, Palaemonetes pugio, Cyprinodon variegatus) organisms. Daphnia pulex was generally the most sensitive animal, but no animal responded to all wastes. Growth of the algae S. capricornutum and S. costatum was affected by all wastes, through either inhibition or stimulation. Some wastes were stimulatory to S. costatum at low concentrations (<1%) but inhibitory at high concentrations (>50%). The concentration of waste that stimulated growth of S. costatum by 20% compared with controls (SC20) was calculated and used with EC50 values for the survival of D. pulex to estimate the potential impact of the wastes in relation to volume of discharge.