An HPLC assay for etoposide in human serum was developed. Serum, spiked with podophyllotoxin (internal standard), was treated with sodium dodecyl sulphate prior to solid phase extraction. Analysis was performed on a 300x3.9 mm Bondclone 10 C18 column coupled with a fluorometric detector (lambda(ex) 230 nm, lambda(em) 330 nm). The retention times for etoposide and podophyllotoxin were 14 and 28 min respectively. The range of assay was 0.5 to 20 microg/ml with a detection limit of 0.2 microg/ml. This assay is suitable for use in clinical studies with etoposide.