Field experiment was conducted during the two successive sea‌sons (1998 and 1999) on roselle plants at Barramoon Experimental Farm, Dakahlia Governorate to investigate the effects of nitrobein (bio‌fertilizer) and other levels of nitrogen fertilizer (0, 40, 60 kg N/fed) combined with potassin (foliage spray) or different levels of potassium sulphate (0, 50, 100 kg/fed). The interaction between the two factors was studied. The most important results were as follows: - Nitrogen (N) sources in addition to potassium (K) sources both at dif‌ferent levels increased plant height, number of branches, number of fruits/plant, sepals weight (fresh and dry), anthocyanin, sugars and protein contents of sepals. - Ammonium sulphate gave significantly tallest plants than nitrobein as a source of nitrogen. - Nitrobein gave less number of branches than ammonium sulphate at 40 kg /fed, however it produced more number of branches than am‌monium sulphate at 60 kg lied. - Nitrobein as a Die-source of nitrogen gave significant higher number of fruits, yield of sepals (fresh and air dried), acidity, anthocyanin, sugars and protein content. - Potassin as a source of potassium caused highly significant increase in most characters (number of branches, number of fruits /plant, acidity, as well as anthocyanin, sugars and protein contents), while potassium sulphate (50 kg /fed) was the most effective than other levels in in‌creasing sepals fresh and air dried weights.