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Existing data conflict as to the capability of stable isotope analysis (SIA) for distinguishing carbon pathways in stream ecosystems. I compiled 803 published measurements of δ¹³C for allochthonous litter and both lotic attached algae and consumers to search for general patterns that transcend individual studies. Half of the fishes and 30% of the invertebrates exhibited δ¹³C values outside the range that could be ascribed to allochthonous litter. The enormous variability in attached algal δ¹³C from −40 to −20‰ (mean ± SD = −29 ± 4) completely enveloped that observed for terrestrial leaf litter (mean = −28 ± 1‰). Therefore, for 50% of the fishes and 70% of the invertebrates it was impossible to discriminate between allochthonous and autochthonous carbon dependency. Faunal δ¹³C did not change in any quantitatively predictable manner with removal of riparian trees. Three conclusions are possible from …