Aim The aim of the in vitro study was the comparison of seven universal adhesives regarding micro-tensile bond strength (µ-TBS) to dentine of primary teeth after three different storage periods. Designs 120 extracted primary teeth were ground flat to expose caries-free dentine simulating a complete caries removal. The samples were bonded with seven universal adhesives (Adhese®Universal, Ivoclar Vivadent; All-Bond Universal®, Bisco; Clearfil™Universal Bond, Kuraray; G-Premio Bond, GC Europe; iBond®Universal, Kulzer; Prime&Bond active™, DentsplyDetrey; Prime&Bond®NT, Dentsply Detrey) and restored with a composite resin build-up (Filtek™ Z250/3M). After 24 hours, 6 months and 12 months storage in distilled water (37°C), the samples were cut in sticks. With a number of 1488 sticks, µ-TBS tests were executed. Afterwards, the fracture mode was analysed under fluorescence microscope with 40x magnification and under a SEM and TEM. Results Compared to the reference group PBNT (32.5 MPa after 6 months; 31.2 MPa after 12 months) two adhesives showed a significantly higher µ-TBS after 6 months (AU:44.1 MPa, ABU:40.9 MPa; ONEWAY-ANOVA-Test, Bonferoni, p<0.05) and one adhesive after 12 months (AU:42.9 MPa, ONEWAY-ANOVA-Test, mod. LSD p<0.05). Whereas GPB revealed a significantly lower bond strength in all storage groups (16.9 MPa after 24h, 15.5 MPa after 6 months, 10.9 MPa after 12 months; ONEWAY ANOVA, Bonferoni, p<0.05), two adhesives (AU, IBU) did not suffer from any pretest failures [PTF] after the different storage periods. GPB showed the largest amount of PTF (5% after 6 months, 12% after 12 months). Conclusion After 12 months, PBNT, IBU, CU, AU and GPB showed significantly lower results compared to initial µ-TBS, whereas AU revealed the highest outcomes in µ-TBS and no PTF. There are further researches nessecary.