The effects of four irrigation water salinities (0.25, 2,5, 5 and 10 dS m(-1) and three potassium fertilizer levels (0, 5 and 10 mmol l(-1)) on yield and same quality parameters of a native Central Anatolian tomato species (Lycopersicion esculentum) were investigated under greenhouse conditions. A fully randomized factorial experiment was conducted between 13th of June and 11th of October 2002 at the Faculty Agricultural Experimental Station of Ankara University. Yield, fruit quality, drainage water salinity and evapotranspiration data were collected. It was found that, butts salinity and potassium fertilizer levels affected fresh fruit yield. The yield decreased with increasing salinity starting at salinity level of 2.5 dS to I and continued to 10 dS to I treatment. The interaction between salinity and K levels was significant. p = 0.05. but the changes in yield did not exhibit any clear result to state that K+ levels had :I direct effect on salinity-induced yield decrease. Plant biomass was affected only by the salinity levels of the irrigation water: the biomass decreased with increasing salinity. Increasing salinity levels resulted in smaller fruit size, higher soluble solid content (SSC) and decreased the pH of the fruit juice, Water consumption decreased with increasing salinity. Increasing salinity levels led to a decrease in water use efficiency (WUE). (c) 2005 Elsevier B.V. All rights reserved.