We have investigated the crystallizability of n-eicosane and n-triacontane in phospholipid bilayers. Our results suggest that there is a relation between the difference in bulk melting temperatures (alkane and lipid) and the crystallizability of the n-alkane. In DMPC and DPPC, C20 co-associated with the lipid acyl tails and therefore transitioned to a gel-like phase together with the lipid. C20 did appear to crystallize in DOPC bilayers, however due to the large fraction of bulk alkane in this sample it was impossible to validate our findings in the same manner as for the other investigated mixtures. C30 was able to crystallize inside DMPC and POPC bilayers. In a sample containing 5 vol% of C30 in DMPC, and only low amounts of water, about 85-90 % of the alkane molecules were incorporated into the bilayer. The remaining chains did not mix with the lipid at all. Of the incorporated n-alkane, approximately 75-80 % crystallized at temperatures slightly below the bulk crystallization temperature. The non-crystallizing chains were instead built into the lipid phase, similar to C20. Inside the bilayer, C30 also crystallized via at least one rotator phase, and an intermediate crystal phase was stabilized compared to the bulk sample. With regards to crystallization kinetics, the formation of the rotator phase was observed to consist of two steps in the membrane: First, pre-organized nalkane chains transitioned as fast as in bulk, but further addition of molecules to the rotator-phase crystal was slowed significantly. This finding suggests that the molecular arrangement of the n-alkane in the lipid bilayer strongly influences the crystallization process.