This study examined the determination of BOD in landfill leachates by dilution (D-Method) and manometric methods (M-Method). The discrepancies between these methods were discussed and statistical tests were carried out. The effects of sample dilution and seeding on BOD results were examined. In comparison to the D-Method the M-Method was found to be more sensitive to increases in chloride and Total Kjeldahl Nitrogen (TKN) concentrations in leachate samples. However, in the M-Method the positive interference of nitrogenous BOD (NBOD) to carbonaceous BOD (CBOD) was more successfully prevented. The BOD rate constant k and the ultimate BOD (BODu) were estimated by non-linear regression. With the M-Method these parameters could be more reliably estimated than the D-Method. Based on these results, suggestions were made for BOD analyses in landfill leachates in future studies.