Tarantula cubensis is known as Cuban tarantula having a venom that contains a diverse mixture of potent compounds with various biological activities. These peptides have been shown to have antitumor activities, therefore features of spider-venom peptides prompted scientists to test them as a potential anticancer drug. The purpose of the study was to investigate the potential cytotoxic effect of Tarantula cubensis venom (Logoplex®) on human cancer cells including prostate (PC-3), lung (H69), breast (MDA-MB-231), and ovarian (OVCAR-3). Moreover, non-tumorigenic MCF-10A cells were used to evaluate the possible cancer cell-specific effect of the extract. The increasing concentrations of Logoplex® were applied for 24, 48 and 72 h. MTT assay was used to assess cell viability. Concentration-response curves and the IC50 values were determined via Graphpad Prism software. Logoplex® caused a time-and concentration-dependent cytotoxic effect in MDA-MB-231, PC-3, OVCAR-3 and MCF-10A cells and the highest cytotoxicity was achieved at 72h. However, in H69 cells, there was a concentration-dependent cytotoxic effect and the highest cytotoxicity was achieved at 24h. IC50 values of Logoplex® in MDA-MB-231, OVCAR-3, PC-3, H69 and MCF-10A cells were determined as 159.3±2.1, 48.9±1.8, 40.2±1.2, 498.3±1.2 and 217.8±2.0 µg/mL, respectively. Logoplex® showed a lower cytotoxic effect against normal cells than the cancer cells suggesting a cancer cell-specific effect. According to the preliminary results of this study, although Logoplex® is a veterinary drug, its cytotoxic effect on human cancer cells suggests that it should be re-evaluated as a potential cytotoxic agent. Analyses to identify functional compounds of Tarantula cubensis venom, and future studies addressing its mechanism of action on cancer cells are recommended.