We searched for possible signatures of top-quark production in 508 e+e- hadronic annihilation events collected at s=52 GeV by the TOPAZ detector at the KEK e+e- collider TRISTAN. The observed hadronic cross section and shape of hadronic events are consistent with the standard-model predictions without top quarks. A lower limit (95% confidence level) on the mass of the lightest top meson is set at 25.8 GeV. © 1988 The American Physical Society.