Several obstacles may delay receipt of targeted treatment in patients with anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC). This study examined the factors associated with delayed initiation of ALK inhibitor (ALKi) treatment and its impact on overall survival (OS) as well as the impact of initiating chemotherapy before biomarker test results.Advanced NSCLC (aNSCLC) patients selected from the deidentified Flatiron Health electronic health record-derived database were stratified into early- and delayed-use cohorts based on initiation of ALKi treatment relative to time since receiving ALK+ biomarker test results; cohorts were further stratified by timing of chemotherapy initiation relative to availability of ALK+ test results. Prescription-time matching (PTM) was used to examine the effect of delayed ALKi treatment and chemotherapy on survival; Cox proportional hazards models adjusting for baseline characteristics before and after PTM were used to examine factors associated with delayed ALKi treatment and the effects of delayed ALKi treatment and chemotherapy on OS, respectively.Comparison of OS between early- and delayed-use cohorts (N = 442 ALK + aNSCLC patients) demonstrated that a >3-week delay in the initiation of ALKi treatment was associated with a >2-fold higher risk of death (adjusted hazard ratio [HR] [95 % CI] 2.05 [1.13, 3.71]. The number of office visits, age factors, and use of chemotherapy were associated with an increased risk of being untreated >3 weeks after ALK+ test results. There were no significant differences in survival outcomes regardless of whether patients received chemotherapy before the ALK+ test result or ALKi treatment (adjusted HR [95 % CI] 1.02 [0.64, 1.63]). Completing the chemotherapy regimen after receiving ALK+ test results did not appear to improve survival (adjusted HR [95 % CI] 0.84 [0.38, 1.9]).Initiating ALKi treatment for aNSCLC patients in a timely manner may have a positive impact on survival outcomes.