Mayurbhanj Chemical Laboratory, Ravenshaw College, Cuttack-753 003 Manuscript received 17 May 1982, revised 2 April 1983, accepted 20 May 1983 On treatment with P2S5, pyrazolone affords thiopyrazolone which on condensation with 4-monobromo- and 4-dibromopyrazolones in 1 : 1 and 1 : 2 ratio, respectively yield mixed bis and \(tris\) derivatives. The bis compounds of thiopyrazolone are also prepared from thiopyrazolone. All these compounds with their oxidised derivatives have been synthesised and characterised by elemental analysis, m.p. and ir spectral data. They are also assayed for their antifungal activity against Pyricularia oryzae and Helmivtkos­porium oryzae. The unsaturated product retards the fungitoxicity. Some of the com­pounds show a very good fungicidal activity and are compared with standard commercial fungicides.