Muscarinic acetylcholine receptors (76 fmol/mg protein) were detected on cultured glia cells (astroblasts) from embryonic chicken brain by specific [3H]quinuclidinylbenzilate (QNB) binding at physiological conditions. The QNB binding (Kd = 9.5 x 10(-11)) to the intact cells seems to be cooperative (nH = 1.98) as shown by graphical methods.