In this study, methotrexate (MTX) was compared with placebo in the treatment of systemic sclerosis (scleroderma, SSc) in a 24 week randomized double-blind trial, followed by an observational trial of 24 weeks duration. Twenty-nine scleroderma patients were allocated to receive weekly injections of either 15 mg MTX or placebo. Patients who responded favourably after 24 weeks continued with the same regimen for a further 24 weeks; those who showed a poor response on placebo were allocated to further treatment with 15 mg MTX weekly, and those who responded poorly to treatment with 15 mg MTX had their doses increased to 25 mg. A favourable response was defined as an improvement of total skin score (TSS) by > or = 30%, of single breath diffusion capacity (DLCO) by > or = 15%, or of the score on a visual analogue scale of general well-being (VAS) by > or = 30%, provided that such improvements were not accompanied by persistent digital ulcerations or worsening of DLCO > or = 15%. Seventeen patients were allocated to MTX treatment and 12 to treatment with placebo. After 24 weeks, a significantly larger number of patients receiving MTX (n = 8, 53%) who completed the first 24 weeks of the study had responded favourably compared to patients receiving placebo (n = 1, 10%, P = 0.03). Comparison of separate variables between the two treatment groups by intention-to-treat analysis at week 24 showed improvement in the MTX group of TSS (P = 0.06) and creatinine clearance (P = 0.07). At week 48, 13 patients received MTX from the start of the study and nine during 24 weeks. From these 22 patients, 15(68%) responded favourably and compared with the start of the study they showed significant improvement of TSS (P = 0.04), VAS (P = 0.02), grip strength of the right hand (P = 0.02) and ESR (P = 0.01). Although the number of patients enrolled in this study is small, these results suggest that in a group of patients with active systemic sclerosis, low-dose MTX seems to be more effective than placebo according to pre-defined response criteria.