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−1, 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+ → KS0π+ decay for normalisation, is
B(B+→pΛ¯¯¯¯)=(2.4+1.0−0.8±0.3)×10−7,
where the first uncertainty is statistical and the second systematic.