As a part of systematic investigation of synthesis and biologically active compounds of thiazolidine (TZD) derivatives containing pyrazole ring system, several new pyrazole-TZD derivatives 8aÀd and 9aÀd have been synthesized. Compounds 8aÀd were prepared from N-substituted TZDs 6aÀd and 1H-pyrazole-4carboxaldehyde 7 by Knoevenagel-type reaction. Treatment of 8aÀd with sodium hydride at room temperature caused dimerization reaction to afford the corresponding spirocompounds 9aÀd. All the synthesized compounds were characterized by spectroscopic analysis. In vitro, the synthesized compounds 8aÀd and 9aÀd were tested for their growth inhibitory activity in A549 lung cancer, B16F10 murine melanoma, and HeLa human uterine carcinoma cells and for their differentiation of 3T3-L1 preadipocytes to adipocytes. The results showed that compound 8c possessed growth inhibitory effect of B16F10 cells (IC 50 ¼ 27 lM) and compounds 9c,d had induction effect on the differentiation of 3T3-L1 preadipocytes.