Triorganotin(IV) pyrazolinates of the type R3Sn(Cl5H12N2O center dot X) [where C15H12N2O center dot X 3(2 '-hydroxyphenyl)-5(4-X-phenyl)pyrazoline {where X = (a); CH3 (b); OCH3 (c); Cl (d) and R Me, Pr-n and Ph}] have been synthesized by the reaction of R3SnCl with the sodium salt of pyrazolines in a 1:1 molar ratio, in anhydrous benzene. These newly synthesized derivatives have been characterized by elemental analysis (C, H, N, Cl and Sn), molecular weight measurement as well as spectral studies [IR and multinuclear NMR (H-1, C-13 and Sn-119)]. The bidentate behaviour of the ligands was confirmed by IR, H-1 and C-13 NMR spectral data. Trigonal bipyramidal structure around tin(IV) atom for R3Sn(C15H12N2O center dot X) has been suggested. The free pyrazoline and a few triorganotin(IV) pyrazolinates have also been screened for their antibacterial and antifungal activities. Some triorganotin(IV) pyrazolinates exhibit higher antibacterial and antifungal effects than free pyrazoline and some of the antibiotics.