A pilot study was undertaken to test whether alpha interferon (alpha-IFN) maintenance could continue to stabilize cancer measurements after induction therapy. Twenty-one patients who achieved stable disease at the end of their induction treatment were randomized to receive weekly maintenance with human lymphoblastoid interferon (HLBI) (3 MU/m2, i.m.) or to be followed and not given interferon. There were 12 patients in the maintenance groups and 9 in the control observation group. There was no time difference in disease progression between the two arms. This article considers the relevance of the stable disease category in trials of interferon.