An evaluation of OCP residue (OCPs = α, β, δ, γ-HCH isomers, p,p’-DDE, p,p’-DDD, p,p’-DDT) from the CauBay River and the KieuKy area in Vietnam was carried out. The CauBay has played an important role in irrigated water supply for agriculture activities in KieuKy downstream. The OCP concentrations of sediment and soil samples were analyzed and results indicated the wide extent of contamination of OCPs in the CauBay (DDTs: 68.35±13.57 ng·g^-1 dw; HCHs: 7.82±2.36 ng·g^-1 dw) and KieuKy (DDTs: 85.24±15.43 ng·g^-1 dw; HCHs: 6.94±1.49 ng·g^-1 dw). This clearly reflected the effects of OCP residue from the CauBay on quality of KieuKy agricultural soil. The OCP composition analyses in the samples reflect their long-time release. The total cancer risk of OCPs in KieuKy soil fell into a very low range, suggesting low risk. However, since OCPs were the species of POPs with more concern in this area, ecological risk assessment should be further investigated.