The distribution of pectin methyl esterase (PE) and endopolygalacturonase (PG) was studied in tomato (Lycopersicon esculentumMill) fruit. Antibodies were raised in rabbits to the PE2 isoform of PE and the PG2 isoform of PG. The antisera were used to probe PE and PG in sections of mature green and ripening tomato pericarp tissue by immunocytology. PE was detected in the cell wall of green and ripening fruit. A comparison with specific and non-specific sera indicated that the PE antigen was largely confined to the cell wall. PG was detected in the cell wall of ripening but not green tissue. Gold label was observed over both the primary wall and the middle lamella, and also over the cytoplasm. In the wall region, no distinctions could be drawn between the distributions of PE and PG, but PG differed from PE in that a significant proportion of the antigen was in the cytoplasm.