Alkylphospholipids (APL) are promising antcancer drugs. We have found that interaction of APL liposomes with cells depends on membrane domain structure, defined by liposome cholesterol content. Liposomes with less than 50 mol% cholesterol fuse with cells, while those with more cholesterol, where the proportion of disordered domains decreases below 10%, don’t. We proposed that fluid domains are responsible for fusion. Results suggest that micelles are not the only reason for cytotoxic effect of APL formulation, but liposomes with less than 50 % cholesterol also contribute to cytotoxicity.