Techniques for the separate, consecutive and simultaneous demonstration of acetylcholinesterase and norepinephrine in cryostat sections are described and discussed. The results, obtained in a variety of tissues from different animal species, are as satisfactory—in terms of sensitivity and sharpness of localization—as those obtained by previously described methods. The simultaneous visualization of both acetylcholinesterase and norepinephrine in the same section provides hitherto unavailable data relative to the exact interrelationship of cholinergic and adrenergic components of the peripheral autonomic nervous system.