Purpose: To determine and compare oral health status, knowledge and attitude among siblings of mentally disabled with siblings of normal healthy children. Materials and Methods: 240 study subjects consisting of 120 each of siblings of mentally disabled and normal, healthy children (control group) matched for age and gender were selected by convenience sampling. Oral health was assessed using the WHO-1997 proforma. A pretested questionnaire (30 items) was used for oral health knowledge and attitude assessment. Statistical analysis was performed using the chi-squared and Mann-Whitney tests. Results: Caries prevalence among the siblings of mentally disabled and control group was 82% (mean DMFT 1.68 ± 1.18) and 45% (mean DMFT 0.58 ± 0.72), respectively (p 0.05). The siblings of mentally disabled children also showed good oral health knowledge (mean 7.1 ± 1.4) and a positive attitude (p 0.05). Conclusion: Siblings of mentally disabled children showed higher caries experience. Knowledge and attitude towards oral health was comparatively good among siblings of mentally disabled children. They exhibited favourable attitudes and involvement in helping their sibling to maintain oral health. Keywords: disabled, oral health, siblings