The aim of this in vitro-study was to evaluate the changes in hardness of precision attachments after exposure to different denture cleaners.In this study 3-month-period influences of denture cleansers with different chemical effects were evaluated. Eight precision attachments were soaked for the equivalent of 3-months of clinical use in 3 solutions (Corega-tabs, 5.25% Sodium Hypochlorite, Aktident-tabs). Control specimens were stored in artificial saliva for the same time period at room temperature. According to manufacturer's instruction the pecision Attachments were exposed to cleansing treatments. The exposures lasting 8-hours for daily-use and 16-hours in artificial saliva for night-use each were conducted 3-month-period. Measurements were made at days 0, 1,7,21 and 90. After that Shore D Durometer (Milton Trading Co) test was applied to test loss of hardness for each. The obtained data were analyzed by using one-way ANOVA and Post hoc Bonferroni test.According to the hardness test results of the precision attachment immersed in 4 different solutions, no statistically significant difference was found between the solutions used. According to the data, the difference between 0. days and 1.-7.-21. -90. days was significant. (p<0.05).According to the results, there was no statistically significant difference in the chemical and physical properties between the dental solutions and the artificial saliva which is the control group in the period corresponding to 3 months of clinical use. However, hardness of all groups decreased in 3 months period.