Objectives: Electricity generation from biomass has become a boom business. However, currently, concerns over their environmental and health impact have emerged. This study aimed to explore these health problems by studying two small biomass power plants in Thailand. Materials and Methods: Data concerning chronic diseases and health symptoms was collected from 392 people by trained interviewers by the use of a questionnaire. Results: Residents living within 1 km from the power plants had a higher prevalence of allergies (Odds ratio = 2.4, 95% CI: 1.5-4.0), asthma (OR = 2.1, 95% CI: 1.0-4.4) and chronic obstructive pulmonary disease (COPD) (OR = 2.7, 95% CI: 1.0-8.4). The risks of other symptoms, itching/rash, eye irritation, cough, stuffy nose, allergic symptoms, sore throat, and difficulty breathing among those living within 0.5 km from the power plants (OR = 2.5-8.5) were even more marked. Conclusions: It has been concluded that without a proper control, pollution from the biomass power plants can cause significant health problems to the nearby residents.