Research background: The effectiveness of Corrective feedback has been a controversial issue and thus a central part of second language writing instruction worldwide.Gap in knowledge and Purpose of the study: It has been argued that the provision of written corrective feedback can affect the complexity of the written text negatively, and the issue is not sufficiently investigated. Therefore, this studyinvestigated the effects of two types of comprehensive written corrective feedback strategies: direct corrective feedback (DCF), and metalinguistic explanation (ME) on L2 learners’ written syntactic complexity.Methods: This study was quasi-experimental and used a pretest-intervention-posttest-delayed-posttest design. Participants were 90 Turkish EFL upper-intermediate learners, whose L2 proficiency and L2 writing skills were controlled by administering the Oxford Placement Test and the IELTS Writing Task 2 test. They were assigned to three groups: DCF, ME, and NF (i.e., no feedback on grammatical errors).The treatment/control period lasted for five weeks. Every week, each participant wrote an essay of argument-led type in class and then received the specified feedback. No work was done on writing for the two-week interval between the posttest and delayed posttest. Lu’s (2010) web-based L2 Syntactic Complexity Analyser was utilised to calculate the syntactic complexity measures. The MANOVA test was utilized to find the results.Findings and Value added: It was revealed the ME group was not significantly different from the NF group. The DCF group significantly outperformed the ME group in the clauses per sentence (C/S) of the texts both in posttests and delayed-posttests. The DCF group also significantly outperformed the NF group in the clauses per T-unit (C/T), complex T-units per T-unit (CP/T), and C/S in posttests, but the positive effect of the DCF on CP/T was not durable after the two-week interval.