Both asthma and obstructive sleep apnea (OSA) are common conditions involving the adults and children population, and have significant impact on the healthcare system. For the last few decades a lot of data emerged in terms of the prevalence between asthma and OSA. The prevalence ranges from 38% up to as high as 70%. Based on the current concepts of bidirectional relationship of OSA and asthma, it is sensible to assume that treating one disorder will result in the other's better control and vice versa. This review will look into the pathogenesis of concomitant OSA and asthma and whether the first line OSA therapy will result in better control of asthma in patients with concomitant OSA. There is growing evidence that continuous positive airway pressure (CPAP) in adults and adenotonsillectomy in children which are recommended as first line treatment of OSA can improve their asthma symptoms. However, further confirmation is necessary with larger randomized control trials to further evaluate both conditions and the treatment effects.