This study evaluates the physico-chemical properties of groundwater in Ogbia, Bayelsa State, Nigeria. Standard field and laboratory methods were followed. The results of the study revealed that the pH value ranges from 6.4 to 7.1 with an average of 6.86 indicating a slightly acidic condition. The concentration level of iron in the study area ranges from 0.1mg/l to 4.2mg/l with a mean value of 1.89mg/l. 13.3% of iron in sampled locations satisfy the World Health Organization (WHO) and Nigerian Standards for Drinking Water Quality (NSDWQ) highest desirable level of 0.3mg/l. The concentration of calcium ranges between 3.0mg/l to 13.1mg/l, with a mean value of 8.83mg/l, while magnesium concentration was from 1.8mg/l to 9.0mg/l, with a mean value of 5.6mg/l. The concentration level of phosphate in the study area ranges from 0.02mg/l to 0.19mg/l, with a mean value of 0.12mg/l. Chloride concentration level in the sampled locations was between 10mg/l to 39mg/l, with a mean of value of 23.8mg/l, all the values recorded were within the permissible WHO and NSDWQ standard of 250mg/l. The low concentration level of chloride in the area indicates that there is no salt water intrusion, hence all the locations have freshwater. The cations were in order of abundance as Na+ > Ca 2+ > Mg 2+ > Fe 2+ > Mn 2+, while anions were in the order of abundance as SO4 > Cl > NO3 > F > NH3 > PO4. Piper Trilinear Diagram for the study area showed that there were mixtures of two types of water with variable concentrations of major ions. These were sodium-chloride type and sodium- sulphate type of water, an indication that the water was from a marine source. Based on the result from this study, there is the need for regular ground water quality monitoring and effective management strategies in the area.