1, 2, 4-Triazine derivatives (3, b) were prepared via condensation of oxazolinones (2a, b) with thiosemicarbazide in acetic acid. Reaction of compound 3b with carbon disulphide, ethyl chloro acetate and p-methylphenacylbromid gives triazolo- [2,1,a]-1,2,4-triazine (4) and triazino- [2,1-a]-1,2,4-triazine derivatives (6 and 8). Acylation of compounds 4, 6 and 8 with acetic acid anhydride yielded the corresponding N-acetyl derivatives (5, 7 and 9). The mass spectral fragmentation patterns of some prepared compounds have been investigated in order to elucidate the structure of the synthesized compounds. Antimicrobial activities and antitumar activity were assayed against test bacteria, fungi and Breast carcinoma cells (MCF-7-cell line).