Effects of Bacillus thuringiensis and nuclear Polyhedrosis virus (NPV) mixture on certain biological aspects of Spodoptera littoralis were evaluated. Both of  2^nd and 4^th larval instars of Spodoptera littoralis were used for that purpose. The mixture of both Bacillus thuringiensis (Dipel 2X) and nuclear Polyhedrosis virus (NPV) were slight effective against 2^nd and 4^th larval instars of Spodoptera littoralis. Generally the Bacillus thuringiensis treated leaves was more effective than other one of nuclear Polyhedrosis virus (NPV) in the respect of larval, pupal mortality and larval; pupal and adult duration. This Bacillus thuringiensis (Dipel 2X) and nuclear Polyhedrosis virus (NPV)  also reduced the fecundity  of alive females and of the treated larvae of the 4^th larval instar of Spodoptera littoralis.