The aim of this study was to determine the objective tumour response rate and duration of response and toxicity of linomide (Roquinimex) treatment in patients with disseminated renal cell carcinoma, pretreated or not pretreated with immunotherapy. From March 1991 to July 1992, 72 patients with metastatic and progressive renal cell cancer were entered of whom 9 (12%) were not evaluable for response. Linomide was given orally, twice weekly, 5 mg during the first week with dose escalation to 10 mg during the second week and 15 mg thereafter. Treatment was continued until disease progression or unacceptable toxicity. No haematological toxicity but slight anaemia was observed. A significant WBC (white blood cell count) increase (P < 0.0001, paired T-test) was found during treatment. The most often reported non-haematological side-effects were: flu-like syndrome (54%, grade III-IV 7%), nausea/vomiting (41% and 3%, respectively) and neurotoxicity (34% and 2%). Most side-effects were of mild or moderate intensity (WHO grade 1 or 2). The objective overall response rate was 4%: 1 CR and 2 PRs. Stable disease was reported for 28 patients (40%). The duration of response was 17, 22 and 30 (CR) months. Median time to progression was 5 months. Linomide at the given dose and schedule is well tolerated, but has limited antitumour activity in metastatic renal cell carcinoma.