From 3, 3', 5, 5'-tetramethyl-4, 4'-bis-1 H-pyrazole, 3, 3', 5, 5'-tetramethyl-4, 4'-methylenebis-1 H-pyrazole and 4, 4'-methylenebis-1 H-pyrazole, the corresponding 1, 1'-dibenzyl and 1, 1'-dihydroxymethyl derivatives have been obtained. Benzylation of 1H-bispyrazoles was carried out by treatment with benzyl chloride under phase transfer conditions. Hydroxymethylation was done by treatment with 37% aqueous formaldehyde either in acidic or in neutral medium. All the products obtained have been evaluated as cytotoxic, and 1, 1'-dibenzyl-3, 3', 5, 5'-tetramethyl-4, 4'-bispyrazole is a powerful cytotoxic agent (ED50=7 μM).