The standard ELISA method for detection of PVY in dormant potato tubers was compared with recently developed methods: (1) a hybridization technique, using a complementary DNA‐probe to PVYN; (2) three modifications of ELISA (standard monoclonal, Flegg&Clark polyclonal or monoclonal). Sap of six Dutch cultivars secondarily infected with PVY was subjected to these methods directly after lifting and after six subsequent one‐week intervals during storage at 20°C. During storage the detectability of PVY decreased, irrespective of the diagnostic method applied. However, decrease was less in susceptible than in resistant cultivars. Although the hybridization technique yielded slightly better results than the standard ELISA procedure, it was time‐consuming and involved hazardous reagents. The modifications of ELISA investigated were not, in general, more sensitive than standard