The dot-ELISA, an immunosorbent assay on nitrocellulose (NC) membranes, was applied to potato viruses. The sensitivity of the test, as determined by visual assessment of the colour reactions in serial dilutions, allowed a reliable detection of the potato viruses M, S, X, Y, A and of potato leafroll virus in leaves of non-potato hosts and potato plants. Tuber extracts taken from the rose end resulted in higher dilution end points than those from the heel end. The test can be performed within two to three hours by using stored NC-membranes precoated with specific γ-globulin. The possibility of storing antigen treated NC-membranes for some days allows the assay to be quickly applied to samples taken in the field.