Previous studies have shown that pseudocholinesterase (PCHE) is low in patients with Crohn's disease (CD). This finding, however, failed to be of clinical relevance due to the wide normal range. PCHE consists of four main molecular forms designated as C1, C2, C3 and C4 according to their electrophoretic mobility. The question of the present study was to assess the influence of CD on the distribution and pattern of the PCHE isozymes. We therefore investigated the electrophoretic separation of PCHE in 16 healthy volunteers (HV), in 15 patients with quiescent CD (QCD; CD activity index: median = 71, interquartile range = 44-122) and in 10 patients with active CD (ACD; CD activity index: 229, 173-304). In most of the cases total serum PCHE activity was within the normal range even in patients with active CD. No changes of the isozyme pattern were found but the percentage distribution was significantly influenced by the inflammatory activity in patients with active CD:C1 (HV: 14.7%, 13.7-18.1%; QCD: 16.0%, 9.8-19.9%; ACD: 8.5%, 2.9-12.5%, p < 0.01) and C2 (HV: 8.0%, 6.7-10.5%; QCD: 9.0%, 7.9-9.7%; ACD: 6.7%, 3.2-8.6%, p < 0.05) were decreased in active CD while the C4 component (HV: 66.8%, 62.5-69.9%; QCD: 63.1%, 54.9-73.8%; ACD: 77.3%, 70.7-90.1%, p < 0.01) was increased. The percentage of the C3 band (HV: 5.7%, 4.6-6.9%; QCD: 6.8%, 4.6-8.4%; ACD: 5.3%, 2.8-6.8%, NS) was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)