A series of 12 new pyrazoline derivatives was prepared from piperidyl chalcones, which in turn were synthesized by condensing 4-piperidin-1-ylbenzaldehyde with diverse acetylthiophenes. The target compounds were characterized by spectroscopic techniques (NMR, IR, MS) and elemental analysis. All the compounds were screened for cytotoxic and anti-HIV-1 activities. Compounds 1c, 1g, 1j, 2a, 2c, 2e, 2g, and 2k demonstrated potential anti-HIV activity but were cytotoxic except for 2e and 2k, which displayed no cytotoxicity in primary human cells. Bioassay results show that the type and positions of the substituents seem to be critical for their cytotoxic and anti-HIV-1 activities.