Adenoid hypertrophy is common in children. Size of the adenoid increases up to the age of 6 years, then slowly atrophies and completely disappears at the age of 16 years. Adenoid hypertrophy in adults is rare. Present study shows that adenoid hypertrophy is now increasing in adults because of various causes. Study has been conducted in the Department of ENT, Jawahar Lal Nehru medical college, Ajmer. Study shows that incidence of adenoid hypertrophy is increasing as the cause of nasal obstruction in adults. This study identified the different causes of adenoid hypertrophy in adult patients. The common causes of adenoid hypertrophy in adults are chronic infection and allergy. Pollution and smoking are also important predisposing factors. Sometimes it is also associated with sinonasal malignancy, lymphoma and HIV infection. Study shows that 21 % of adult nasal obstruction is due to adenoid hypertrophy. But in case of the patient with chronic tonsillitis only 8 % were associated with adenoid hypertrophy. Males are more commonly involved (80 %) then female, may be because of outdoor activities and more commonly exposed to pollutants. And most commonly involved age group is 16–25 years. Majority of the cases with adenoid hypertrophy are associated with infection and allergy i.e. allergic rhinitis in 38 % cases descending infection in 28 % cases, and ascending infection in 22 % cases. Association of sinonasal tumors, are rare i.e. 4 % each. So any cases of adult adenoid hypertrophy should be treated seriously to exclude the dangerous causes.