Background: The association between arginase I (ARG1) and arginase II (ARG2) genes and asthma has been reported in previous studies, but associations between polymorphisms in ARG genes and preschool wheezing (PSW) phenotypes are unknown. Objective: To examine the association between genetic variation in ARG1 and ARG2 genes and PSW phenotypes and to compare results with asthmatic patients. Methods: We enrolled 102 patients and 86 healthy controls. The patient group included three subgroups: episodic wheezing (EW) (n = 42, median age 41 months), multiple-trigger wheezing (MW) (n = 41, median age 39 months), and asthma (n = 19, median age 72 months). We genotyped six single nucleotide polymorphisms (SNPs) in ARG1 and six SNPs in ARG2. Eighteen haplotypes for ARG1 and 31 haplotypes for ARG2 were constituted, and the distributions of SNPs and haplotypes in patients and controls were analyzed. Results: The frequency of homozygote cytosine-cytosine genotype of the ARG1 rs2781667T>C SNP in the EW group was significantly lower than controls (p = 0.006) [OR (95% CI): 0.26 (0.10-0.66)], the MW group (p = 0.002) [OR (95% CI): 0.19 (0.06-0.52)], and asthmatics (p = 0.025) [OR (95% CI): (0.22 (0.06-0.75)]. ARG1 haplotype 4 was more frequent in the MW group, asthmatics, and controls than in the EW group (p < 0.0001) [OR (95% CI): 7.77 (2.54-23.7)], (p = 0.036) [OR (95 %CI): 4.31 (1.15-16.15)], and (p = 0.030) [OR (95% CI): 3.44 (1.20-10.0)]. Conclusion: Variations in ARG1 gene may be useful in discriminating PSW phenotypes.