The use of an inert supporting matrix is necessary in order to obtain 50 pm vibratome tissue slices for cytochemistry studies when using small tissue samples. Five matrices were assayed: granulate agar, purified agar, agar-agar, agarose and gelatine at different concentrations. The best results were obtained with agar-agar and agarose which both gave good tissue stability, providing an easy handling of samples and resulting in more homogeneous texture. These requirements are important if good slices are to be obtained which will be useful for cytochemistry, immunocytochemistry and histochemical tracing studies.