Few systematic studies have been made of amounts or of the composition of gingival crevicular fluid (GCF) from different sites or of the stability of GCF parameters over time. These data are needed to better understand the relation of GCF composition to periodontal health status. This report gives the volume and the amounts of lactate dehydrogenase (LDH), aryl sulfatase (AS) and neutrophil elastase (NE) for GCF collected from 6 samplings of 6 standard gingival sites in 11 young adult subjects over a 6-week period. Attachment loss (3 mm) was noted at only 1 of the 66 sites. The mean gingival index of the 11 subjects ranged from 0.33 to 1.67. The GCF volume and activity/sample of LDH and AS but not NE differed among subjects. However, differences among subjects were not found when the GCF enzyme activities were expressed as activity/microliter GCF. GCF volume and LDH, AS and NE activity all differed among the 6 sites when the activities were expressed as either quantity/sample or microliter GCF. These data show that differences among sites must be carefully considered in evaluation of GCF data. Fluid volume and LDH, AS and NE activity all varied from sampling to sampling. However, differences among sites were retained throughout the experimental period.