Liquid phase epitaxy of (AlzGa1−z)xIn1−xAsyP1−ypentanary is reported for the first time. The pentanary of (Al0.05Ga0.95)0.55In0.45As0.07P0.93is grown successfully on a (100) oriented GaAs substrate by liquid phase epitaxy using a two‐phase solution growth technique atTg=845 °C. Existence of Al in the epitaxial layer is determined by x‐ray microanalyzer, x‐ray diffractometer, and photoluminescence. The growth conditions of the (AlGa)InAsP pentanary are also discussed.