The losses due to the weeds on the fields of Oriental type tobacco can reach the level of 50%; this problem requires a reasonable usage of the herbicides and cultivations. Thorough researches were made on the cultivar Djebel 292, between 1987 and 1990, concerning the influence of a three factors complex (herbicides : Mecloran 35 EC and Diizocab; time of application : 7, 5 and 3 days before emergence; manual cultivation : 2 and 3) on the yield and quality of the tobacco. The application of Mecloran 35 EC (alachlor) and Diizocab (butylate) made in Rumania, using 6 L/ha, didn't lead to injury of the tobacco plants, cultivar Djebel 292, they had a normal growth and development, specific to this cultivar. The application of Mecloran 35 EC, using 6 L/ha, lead to a significant raise of yield of 123.5 kg/ha, compared to Diizocab, 6 L/ha. Compared to the application of the two products at 7 days before emergence, application at 5 days leads to a significant loss of yield of 191.3 kg/ha, and application at 3 days to a very significant loss of yield of 539.8 kg/ha. Increasing the number of manual cultivations from 2 to 3 resulted in a very significant raise of yield of 295.8 kg/ha. The two tested herbicides didn't influence significantly the chemical composition of the unprocessed tobacco or its industrial quality. Analysing the rate of weed density, it is obvious that the best choice is the application of the two herbicides at 7 days before emergence. Generally, no obvious differences were recorded concerning the influence of the herbicides on the enzymatic activity in the soil; the values recorded for the application of Diizocab were fairly higher than for Mecloran 35 EC.