Objectives: Aim of the present study was to evaluate the effect of saliva contamination and in vitro demineralisation on microtensile bond strengths (mTBS) of one self-etching (Delton) and two multi-step fissure sealants (Fissurit F, Smartseal) to enamel. Methods: 135 freshly extracted molars stored in saline were included. The molars were sectioned at the cement-enamel junction and the roots were discarded. The crowns were sectioned in the mesio-distal direction, and flattened until a flat enamel surface area was reached. All specimens were randomly assigned to nine experimental groups of 15 samples each: Fissurit (FC, FS, FD), Smartseal (SC, SS, SD), Delton (DC, DS, DD). In groups FS, SS, DS saliva was placed on the enamel before the sealant was applied. In groups FD, SD, DD the enamel surface was demineralised using acidified gel technique (HEC, pH 4.8, 37°C) for 14 days before fissure sealant application. Groups FC, SC, DC served as controls. In these groups the enamel was sound. All sealants were applied as recommended by the manufacturer. MTBS was measured 15 minutes after application of the fissure sealant using an universal testing machine. Results: Statistical analysis showed a significant influence of the used sealant and the contamination on mTBS (p 0.001, ANOVA). Saliva contamination and demineralisation decreased mTBS. In case of Fissurit and Smartseal this increase was significant (p 0.05, Tukey's test). Conclusions: All fissure sealants used in this study were able to establish mTBS on enamel. Saliva contamination and in vitro demineralisation showed a significant impact on mTBS. Palabras clave: Cobalt-Chromium dental alloys, precious metals