Many in vivo studies showed the accumulation of PFC particles in reticuloendothelial cells of target organs such as spleen, lungs and liver. Surprisingly, an uptake of PFCs particles by liver parenchymal cells as well was described by some authors. In order to clarify whether Kupffer cells and/or liver environmental factors could be involved in particle uptake we exposed cultured rat hepatocytes to Fluosol 43. PFC particles were noted, after a 3-hour incubation, in lysosomes. This result suggests that more attention must be paid to liver toxicity of PFC blood substitutes. Isolated mouse myocytes were exposed as well to Fluosol 43 for 3 hours. Preliminary results confirm the absence of the particle uptake previously noted also in our in vivo studies on rat and guinea pig heart-lung preparation. The possible subsequent absence of cytotoxicity at myocardial level could underline the reliability of using optimized PFCs as components of cardioplegic solutions in open heart surgery.