Anticancer chemotherapy is limited by adverse side-effects resulting from toxicities to normal tissues. Targeted delivery of drugs to diseased tissues in vivo would help to reduce these side-effects. Liposomes containing lipid derivatives of polyethylene glycol (sterically stabilized liposomes) have circulation times that are sufficiently long to allow for effective in vivo drug delivery, and are discussed in this review by Theresa Allen. Sterically stabilized liposomes, containing entrapped doxorubicin, targeted to squamous cell lung carcinoma by means of specific antibodies attached at the liposome surface are capable of reducing tumour burden to a significant extent and eradicating tumour in a significant percentage of mice.