The extraction of lysophosphatidylcholine from canine heart and the storage of lysophosphatidylcholine in total lipid extracts were investigated. The lysolipid was effectively extracted from canine heart by chloroform/methanol (1/2) and the maximum recovery of the lysolipid was 89-92%. Changes in levels of the lysolipid were observed when the tissue was stored at 0 degree C for 60 min or at -20 degrees C for 7 days. An alteration in the lysophosphatidylcholine level was also observed when the lipid extract from the heart was stored in theoretical lower phase (chloroform/methanol/water; 86/14/1). In order to accurately assess the level of lysophosphatidylcholine in the canine heart, the lipid should be extracted immediately from fresh tissue and the lipid extract stored in chloroform/methanol (2/1) or without solvent under nitrogen prior to separation and determination.