This study was conducted in order to determine the distribution ratio of PLRV, PVS and PVY (PVYN, PVYo and PVYc) in the seed potato tubers used for planting material in the important potato production regions of Turkey and observe the symptoms caused by single or mixed infection of these viruses under field condition. Firstly, over 880 leaf samples were tested by using virus-specific polyclonal antibodies. Secondly, 83 samples found to be infected with PVY in the result of first ELISA were retested by using PVYo, PVYN and PVYc-specific monoclonal antibodies. The ELISA results showed that seed potato tubers used for planting material was infected with at the rate of PLRV (14.2%), PVX (11.8%), PVS (4.6%) and PVY (17.7%). On the other hand, the result of monoclonal antibody for PVY-strains showed that the frequency of PVYN and PVYo were (13.4%, 4.3%) but PVYc was not found. Under field condition, plants infected with PLRV exhibited the rolling of young leaves, upright growth and pinky color but PVS did not cause any distinct symptoms. PVX alone or the combination of PVX with PLRV, PVS and PVY caused mild or severe mosaic symptoms on all cultivars. PVY induced yellowing of leaves, leaf drop streak, veinal necrosis on some plants from all cultivars, however, some plants did not develop any distinct symptoms in case of infected with PVY. The combination of PVY and PVX caused more severe mosaic, rugosity and reduced of leaf size. When plants infected with PVY and PLRV exhibited yellowing of leaves, leaf drop, dwarfing, rolling of leaves and rogositiy. However, some plants from Morfona and Granola cultivars died. On the other hand, the symptoms on plants infected with PVS and PLRV or PVS and PVY were similar to single infection of PLRV and PVY.