Eastern red-backed salamander (Plethodon cinereus; RBS), known to be one of the most common vertebrates within its geographical range, is an amphibian species commonly used as indicator of forest ecosystem health. Its suitability in this role is based in part on previous studies showing that it is sensitive to changes in habitat such as increased acidity. The occurrence and body sizes of RBS were examined under coverboards, over a 5 y period, in a northern hardwood forest of Québec (Canada) having a highly acidic forest floor (pH  =  3.7 ± 0.4). During this period, 565 RBS were captured. Encounter rate (29%) of salamanders under coverboards was considered very high, as compared to similar studies. Also, 87% of youngs of the year and 83% of adults were found under coverboards that had a forest floor pH ≤ 3.8, representing 79% of all coverboards. Weight and length of RBS measured in this forest ecosystem are among the highest values reported in the scientific literature for this species. Both the relatively high body parameter values and occurrence of RBS in this acidic environment contradict previous studies that demonstrated the negative influence of soil pH on the occurrence and health of RBS. These observations indicate that a highly acidic habitat may support a healthy RBS population. Moreover, the studied forest seems to have the lowest pH yet reported for a habitat known to support this salamander species. Given that RBS has been widely used as an indicator for monitoring forest ecosystems in recent years, this new information on microhabitat tolerance should be considered for correctly using this species as indicator of forest health and soil acidity.