A search for the rare two-body charmless baryonic decay B → pΛ¯ is performed with pp collision data, corresponding to an integrated luminosity of 3 fb , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of B →pΛ¯ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the B →K π decay for normalisation,(Formula Presented.)where the first uncertainty is statistical and the second systematic.[Figure not available: see fulltext.]. + −1 + + 0 + S