The reaction of flue-cured tobacco to fertilization by organic and mineral fertilizer was studied in experiments conducted over a period of three years, from 1984 to 1986. The investigations were carried out in north Croatia, on the sandy soils low in humus, where most of the Yugoslavian flue-cured tobacco fields (11 000 ha) are located. The experiments included seven treatments : 1) Control (no fertilized tobacco), 2) 350 kg NPK 7:14:21, 3) 350 kg NPK 7:14:21 + green manure crop, 4) 10t manure, 5) 20 t manure, 6) 10 t manure + 350 kg NPK 7:14:21 and 7) 20 t manure + 350 kg NPK 7:14:21, arranged in four randomised blocks. The results obtained over the three-year period indicate the positive effect of lower rates of organic fertilizer on the yield and quality of tobacco due to the improved air and water properties of the soil. When the combinations of organic and mineral fertilizer were added, the same or higher yields were obtained and the tobacco tended to be of better quality compared to the other treatments. In 1984 and 1986, all fertilized treatments had a significantly higher nicotine content while reducing sugars were slightly higher than control treatments through 3 year period. Organic fertilizer applied in the range of 10-20 t improved the water retention and the soil structure and also allowed tobacco roots to develop better.