OBJECTIVE: To determine whether temporal trends exist for short-acting beta agonist (SABA), oral corticosteroid (OCS), and anti-inflammatory prescription fills in children with persistent asthma. METHOD: This was a longitudinal analysis of pharmacy record data and health information data obtained by parent report over 12 months for children with persistent asthma 2 to 9 years of age. Eligible children had to report current nebulizer use and one or more emergency department visits or hospitalizations within the past 12 months. RESULTS: Children were primarily African-American (89%), male (64%), received Medicaid health insurance (82%), and were a mean age of 4.5 years (SD 2.1). Few families (11%) reported any problems paying for their child's asthma medications at baseline or at the 12-month follow-up. There was a high degree of association between filling a rescue (SABA or OCS) and controller (leukotriene modifier, inhaled corticosteroid, cromolyn) medication during the same month for all months with Pearson's correlation coefficients ranging from a low of 0.28 for October to a high of 0.53 in September. Short-acting beta agonist fills were significantly more likely to be filled concurrently with inhaled corticosteroid fills. However, significantly fewer prescription fills were obtained in the summer months with an acceleration of medication fills in September through December and an increase in early spring. CONCLUSIONS: There was a summer decline in both inhaled corticosteroid and SABA fills. Timing of asthma monitoring visits to occur before peak prescription fill months, i.e., August and December for an asthma "tune-up," theoretically could improve asthma control. During these primary care visits children could benefit from more intensive monitoring of medication use including monitoring lung function, frequency of prescription refills, and assessment of medication device technique to ensure that an effective dose of medication is adequately delivered to the respiratory tract. Additionally, scheduling non-urgent asthma care visits at pre-peak prescription fill months can take advantage of "step down" during decreased symptom periods and when appropriate restart daily controller medications to "step up" prior to peak asthma periods.