BACKGROUND: Fecal occult blood tests have been widely used for colorectal cancer screening. In recent years, many laboratories have used automated fecal occult blood test analyzers using immunologic techniques for convenience, fast reporting and quantitative handling. Hemo Techt NS-Plus C15 (NS-Plus C) (Alfresa pharma Co., Japan) is a newly-introduced automated fecal occult blood test analyzer using colloidal gold agglutination methods. We evaluated the performance of NS-Plus C. METHODS: The linearity, precision and carry-over rate of NS-Plus C were evaluated. We performed parallel test between NS-Plus C and HM-JACK (Kyowa Medix Co., Japan) using 219 stool specimens. RESULTS: The linearity was good (R2=0.998) and coefficient of variation (CVs) of within-day precision were 2.61% and 2.07% in low and high concentration, and between-day CVs for each group were 3.18% and 1.63%, respectively. Carry over rate was 0% and concordance rate between NS-Plus C and HM-JACK was 98.6%. CONCLUSIONS: NS-Plus C showed good performance for linearity, precision, carry over rate and comparison study. Therefore, this is believed to be a highly reliable measurement system for fecal occult blood test.