We have investigated the presence of neurotensin receptors in human meningiomas by in vitro binding autoradiography. Ten of the 12 meningiomas tested displayed specific [3H]neurotensin binding. All meningothelial (n = 3) and transitional (n = 5) meningiomas were positive, whereas only 2 of the 4 fibroblastic meningiomas showed measurable concentrations of neurotensin binding sites. Within the tumors, [3H]neurotensin binding was preferentially observed in syncytial areas. Saturation experiments showed that the maximal binding capacity (Bmax) greatly varied among tumors, ranging from low values to more than 290 fmol/mg of protein. All positive tumors had neurotensin binding sites with a dissociation constant (kd) within the nanomolar range and a pharmacological specificity for [3H]neurotensin similar to neurotensin receptors.