Objective: to assess the color stability of artificial teeth after immersion in different staining solutions and to determine the effect humic acid on removing stain from teeth. Background: Old denture wearer needs effective, easy-use and safe denture-cleaning material. Material and Methods: Sixty maxillary incisors were divided into the three groups according to staining solution as tea (T), cherry juice (CJ) and cola (C). Baseline color measurements were performed with a spectrophotometer. Specimens were immersedin a staining solutions for 14 h (2 h _ 7 days) and then second color measurements were performed. Each group was further divided into four subgroups according to denture cleanser as Corsodyl (Cr), Corega tablet (Ct), humic acid (H) and distilled water (W) (n=5). Specimens were immersed in denture cleansers for 8h and third color measurements were made. Thus, the weekly simulation period was completed. This cycle was repeated 12 times to simulate a 3-month time period and measurements were performed. Color differences were calculated and data were analyzed with 2-way repeated measures ANOVA and Tukey tests. Results: The highest color difference after staining was noted in T. After the 12-times repeated immersion beverage and cleanser cycle, discoloration of teeth stained in beverages and cleaned with different solutionswas demonstrated. H and W were more effective than others for the teeth stained in T and Cj. However there was no difference among the cleaning solutions for teeth stained in C. Conclusions: Humic acid could be used as an alternative "natural" solution for denture-cleaning agent.