Abstract The addition of taurine produced different effects on 45Ca 2+ accumulation in frog retinal rod outer segments isolated in a Krebs-bicarbonate buffer depending on exogenous CaCl 2 concentration. At low external calcium (0·1 m m), 25 m m exogenous taurine produced an ATP-dependent increase in 45Ca uptake of 60–80% over control values. At high external calcium (2·5 m m) exogenous taurine (2·5–25 m m) decreased 45Ca uptake 25–50%; this effect was partially prevented by ATP. 10 m m GABA, glycine or β-alanine did not affect 45Ca transport in similar conditions. Inhibition of Ca transport by taurine was maximal at pH 7·4, although it was observed at pH from 6·4 to 8·2. Both taurine effects were observed after 1 min of incubation and increased up to 10 min.