Recently, functional genetic variants of the PTGDR gene have been associated with asthma. The objective of this work was to study polymorphisms of the promoter region of PTGDR and their haplotype and diplotype combinations in a Spanish population of children with asthma. In this study, 200 Caucasian individuals were included. Asthma was specialist-physician diagnosed according to the ATS criteria. The polymorphisms were analyzed by direct sequencing. In the study, the new polymorphism (-613C > T) in the promoter region of PTGDR was analyzed. The CT genotype was more common in controls (17%) than in patients with asthma (1%) (p-value = 0.0003; OR, 0.057; 95% CI, 0.007-0.441). The CCCT CCCC diplotype (promoter positions -613, -549, -441, and -197) was more frequent in the group of patients with asthma [Fisher's p-value = 0.012; OR, 10.24; 95% CI (1.25-83.68)]; this diplotype is unambiguous. To our knowledge, this is the first study of -613C > T PTGDR polymorphism in patients. This analysis provides more complete information on influence of diplotype combinations of PTGDR polymorphisms in asthma.