This study determined whether or not students with dyscalculia had difficulty with attention as measured by the Conners' Computerized Continuous Performance Test (CPT). Fifty-six control subjects and 27 subjects with dyscalculia were administered the CPT. Performance was measured using percent omission errors, percent commission errors, mean response time, SE of response times (SE-RT), and a calculated overall attention index (CPT Index). Compared with controls, subjects with dyscalculia had higher CPT Index scores, made more omission errors, and had more inconsistent response times (SE-RT). Multiple regression analysis of arithmetic scores showed that SE-RT and percent commission errors were the only CPT measures that contributed to the arithmetic scores. Problems with attention, as measured by the Conners' CPT, were associated with lower arithmetic achievement scores. Students who have difficulties in arithmetic may have more attentional problems than other children, and students with attentional difficulties may be at risk for difficulties in arithmetic.