There is one study on the association of the CD40 G > T (rs4810485) single nucleotide polymorphism (SNP) as a risk factor of systemic lupus erythematosus (SLE). Therefore, we studied the prevalence of the CD40 G > T SNP in patients with SLE (n = 261) and controls (n = 545) in a Polish population. We did not find significant differences between the CD40 G > T genotype and allele frequency in patients with SLE and healthy individuals. However, the frequency of the CD40 TT and GT genotypes was statistically different between patients with arthritis and neurologic manifestations and patients without these symptoms (OR = 0.2009 (95% CI = 0.07547-0.5348, p = 0.0004, p (corr) = 0.0068) and OR = 0.2876 (95% CI = 0.1371-0.6031, p = 0.0005, p (corr) = 0.0085) respectively). Our observations indicate that the CD40 T variant might be negatively associated with some clinical disease manifestations in patients with SLE.