Several attempts have recently been made to develop chronotherapy for nocturnal asthma, using theophylline, inhaled corticosteroid, inhaled anticolinergic agent and beta 2-agonist. Pharmacological chronotherapy is the administration of medication according to biological rhythm to maximize pharmacological effects and minimize side effects. The circadian rhythm of biological rhythms is particularly important in understanding the declined changes in lung function of asthmatics at night. Since diurnal variations of PEF obtained from asthmatics, include circadian rhythms at a high rate, it is thought that PEF may be suitable for evaluating the effect of chronotherapy. Chronotherapy of a once-daily evening dose of a new controlled-release theophylline preparation, that achieves to peak blood concentrations at 10-12 hours after dosage, effectively improved the values of PEF and symptoms of nocturnal asthmatics. Hereafter, it is speculated that more effective therapy will be developed by using chronopharmacological designed drugs.