Two series of substituted phenothiazine derivatives were synthesized in order to obtain better antimicrobial agents.  The titled compounds 3a, 3b, 3c, 3d, 3e, 3f and 3g, 3h, 3i, 3j were obtained by using o-chlorobenzoic acid and m-dichlorobenzene as starting material respectively. These compounds were synthesized according to Ullmann and Mannich base reaction. The structures of all these compounds were confirmed by spectral analysis. The titled compounds were screened for antibacterial and antifungal activities. Except 3e all compounds have shown good antibacterial activity against gram-positive and gram-negative bacteria. However, all these compounds have shown good antifungal activity against A. niger. The compound 3g has shown greater antifungal activity than the standard.