Radon level was studied in Aizawl district using solid state nuclear track device (SSNTD). SSNTD consists of plastic cylinder, called ‘dosimeter’, which detect alpha particles waves (nuclear track) emitted from radon. This nuclear track was read with park counter. seasonal variation throughout the year was recorded. Other than tobacco smoking, radon is established to be a major carcinogen of the lung cancer. Aizawl district has the highest incidence (in percentage) of lung cancer in India. This study may show the role of radon in the development of cancer in Aizawl district.