By Following controlled experiments conducted in vegetation pots, the effect of chlorine used as potassium chloride upon yield and especially upon the smoking quality of tobacco was assessed. This problem occurred following the diminution of tobacco burning capacity due to the high content of chlorine in some soils. It is known that in soil there are amounts of chlorine from the use of the complex fertilizers on crops, fertilizers that have in their composition potassium as potassium chloride. The yearly use of these fertilizers led to the increase of chlorine content in the soil, beyond the limits admitted for tobacco. This study was conducted in the vegetation house and aimed the influence of chlorine upon the physiological and biochemical processes in tobacco, the dynamic of the transformations happened during growth and development, the disorders which can occur as a result of the deviation from a balanced nutrition. By the applied treatments, it was aimed to establish the best doses of chlorine fertilizers, in order to ensure a yield of tobacco leaves of best quality and with a high burning capacity. To assess the effect of chlorine on tobacco, a complex experiment was conducted in the vegetation house using two sources of potassic fertilizer, which were potassium sulphate (K2SO4) and potassium chloride (KCl), respectively. Besides the potassium doses nitrogen and phosphorus were applied, as follows: a. potassium doses :a1: 0 grs; 1 gr; 3 grs; 6 grs; 9 grs; 12 grs of K/pot, as potassium sulphate;a2: 0 grs; 1 gr; 3 grs; 6 grs; 9 grs; 12 grs of K/pot, as potassium chloride; b. phosphorus doses : 0 grs and 3 grs of P/pot, as monosodic phosphate ; c. nitrogen doses : 0 grs, 3 grs and 6 grs of N/pot, as ammonium nitrate. Thus, were achieved 72 combinations of fertilization, for each combination having 4 pot - replications. As the nutritive substrate is was used a mixture of sand and soil in the ratio 1:1,5. Care was taken that the soil should not contain any trace of fertilizer, being gathered from forest. The vegetation pots were filled with around 8 kgs of nutritive mixture. The tests were made with cultivars Djebel 292 and Ghimpati 55. After the experiments, it was found that the potassium used as potassium chloride led to a strong effect of reduction of tobacco burning capacity, so that at higher doses the burning was very poor and even null (the burning duration below 1 second). Connected with these results, the negative effect of the complex fertilizers which contain potassium chloride on the tobacco burning is obvious. Based on the obtained results, the best doses of chlorine fertilizers can be set, with positive effect upon yield and smoking quality. To obtain tobacco of high quality is it advisable to use small amounts of chlorine fertilizers or even their complete elimination.