To determine the clinical relevance of 'scleroderma-pattern' (SD-pattern) in mixed connective tissue disease (MCTD), 63 (MCTD) patients (Kasukawa's criteria) were consecutively selected. The main inclusion criterion was availability of previous nailfold capillaroscopy (NC) five years before inclusion. At entry, organ involvement and autoantibody evaluation were performed. The mean age and disease duration were 45.3 +/- 10 and 8.45 +/- 5.42 years, respectively. SD-pattern was observed in 41 patients at entry (65%) and in 45 at previous NC (71.5%), P = 0.20. Ten patients (16%) changed NC, seven normalized, and three developed SD-pattern. Disease duration, number and frequency of organ involvement were similar in patients with and without SD-pattern. In contrast, analysis of each SD-pattern parameter revealed a significantly lower frequency of moderate/severe avascular areas (AA) at entry compared to previous examination (26.5 versus 53%, P = 0.013). Moreover, 76% of patients with interstitial lung disease (HRCT) had AA at entry, whereas only 24% of patients with this alteration did not have this NC finding (P = 0.017). Furthermore, reduced capillary density was more frequently observed in patients taking immunosuppressive therapy than in those without this medication (66.7 versus 33.3%, P = 0.001). NC in MCTD is a dynamic process and analysis of each SD-pattern parameter seems to be a good indicator of lung involvement and disease severity.