The synthesis of anithiactin A has been achieved in four steps. Several closely related analogues were synthesised and their biological activity against colon and breast cancer cell lines evaluated. Anithiactin A was found not to be cytotoxic even at a high concentration (100 μM); however, two 4-substituted phenyl thiazoles were found to be moderately cytotoxic at 10 μM. Based on these results, 4-substitution on the phenyl group appears to be critical for cytotoxicity. However, the exact electronic and structural requirements are unclear.