Immunogold labelling was used to study the organisation of the 1 integrins on osteosarcoma-derived osteoblasts (Saos-2 and MG-63). Monolayers of cells were prepared in multiwell culture plates on both uncovered and collagen-covered coverslips, and 1 integrins were primarily labelled using mouse monoclonal antibodies to 1 integrins. Indirect immunofluorescence labels using an anti-mouse fluorescein-conjugated goat antibody showed an even distribution of the 1 integrins on the cell membranes of all cell types used. A concentration of 2g/ml of the primary antibodies and a 1:100 dilution of the secondary antibodies were determined as the optimal concentration for labelling to use with indirect localisation of the primary antibodies gold conjugated to goat anti-mouse antibodies and viewed under an electron microscope. Ten nanometre gold particles were used for transmission electron microscopy (TEM) and 40nm gold particles for scanning electron microscopy. TEM showed that 1 integrins were mainly clustered on the cell membrane processes with less labelling on the cell membranes themselves. The distribution of 1 integrins on osteosarcoma cells supports the concept that integrins may function by forming focal adhesions at the site of the cytoplasmic membrane processes.