Formaldehyde vapor levels were evaluated in a histological fixative laboratory and environments where anatomical pieces treated with this fixative are stored or handled. Formaldehyde concentration in the air may reach values up to 9 times higher than that established (0.3 ppm) by the international official surveillance bureaus. These results emphasize the need to perform these activities in an environment with good exhaust conditions in view of the deleterious effects of formaldehyde. Therefore, we designed a practical modular mechanical device to carry out transcardiac fixative perfusion inside an exhaust hood. This device is coupled to accessories that help surgical procedures, animal head tissue cooling and collection of organic and chemical residues for posterior discharge or treatment. In addition, as it was designed to be readily assembled and disassembled it releases the hood for other tasks. (C) 1997 Elsevier Science B.V.7216570