The influence of irrigation on the yield, unit value and chemical quality of flue-cured tobacco was investigated on the experimental field of the Tobacco Institute Zagreb in Pitomaca during 1990 and 1992. The experiment was set up according to the block method with four repetitions. In the experiment the irrigation was applied at the moment when soil moisture content dropped to 40%, 60% and 80% of physiologically active water. In the other three treatments of the same experiment the same irrigation procedure was applied but additionally a leaching of nitrogen from the root zone was simulated with application of 60 l/m2 of water in the blossoming stage. Tobacco wich was not irrigated was used as a control. Tobacco was topped, sucker control and cultivation were done manually, and there were no weeds. The research results in 1990 showed that the irrigation procedure gave an increase in the yield (3-27%), unit value (44-69%) and reducing sugars content (50-94%), but a decrease in the nicotine content. The results in 1992 showed an increased yield (13-40%), a better quality (8-28%) and a higher reducing sugars content (19-40%), as well as a lower nicotine content in the middle leaves.