Department of Chemistry, Saurashtra University, Rajkot 360 005 Manuscript received 24 June 1985, revised 14 July 1987, accepted 18 September 1987 We have synthesised N-arylaminoacetylbenzimidazole/sulphadiazine or sulpha­methazine by the condensation of N-chloroacetylbenzimidazole or 4-N-chloroacetyl­sulphadiazine derivatives with different aromatic amines. N-Arylbenzimidazol-1- yl/sulphadiazin-4-yl- or sulphamethazine-4-yl-acetamides were also obtained by the condensation of benzimidazole or sulphadiazine derivatives with N-chloroacetylated arylamines. The products were screened for antimicrobial and anthelmintic activities. The constitution of the product was supported by ir spectra and elemental analysis.