The indoor and outdoor radon progeny concentrations were investigated at a semi-hilly area of Pathankot in Punjab using the method of beta particle counting of aerosol samples collected on a glass micro-fiber filter. A linear relation was found between indoor and outdoor equilibrium equivalent concentrations of radon-222 (EEC Rn ) with correlation coefficient of R=0.9. The indoor and outdoor EEC Rn levels were also studied as a function of outdoor temperature. The variations with temperature in both cases showed negative correlation with correlation coefficient of R=-0.66 and R=-0.73, respectively. The ratio of outdoor to indoor EEC Rn investigated as a function of absolute difference of indoor and outdoor temperatures (|T in –T out |) resulted in a correlation coefficient of R=0.52, which is positive. The indoor EEC Rn was also estimated from an empirical relation based on transport of inside and outside radon progeny through ventilation. The measured inside EEC Rn agrees well with the computed value.