The psychological impact of predictive genetic testing for hereditary non-polyposis colorectal cancer (HNPCC) was assessed in 114 individuals (32 carriers and 82 non-carriers) attending familial cancer clinics, using mailed self-administered questionnaires prior to, 2 weeks, 4 months and 12 months after carrier status disclosure. Compared to baseline, carriers showed a significant increase in mean scores for intrusive and avoidant thoughts about colorectal cancer 2 weeks (t = 2.49; p = 0.014) and a significant decrease in mean depression scores 2 weeks post-notification of result (t = -3.98; p < 0.001) and 4 months post-notification of result (t = -3.22; p = 0.002). For non-carriers, significant decreases in mean scores for intrusive and avoidant thoughts about colorectal cancer were observed at all follow-up assessment time points relative to baseline. Non-carriers also showed significant decreases from baseline in mean depression scores 2 weeks, 4 months and 12 months post-notification. Significant decreases from baseline for mean state anxiety scores were also observed for non-carriers 2 weeks post-notification (t = -3.99; p < 0.001). These data indicate that predictive genetic testing for HNPCC leads to psychological benefits amongst non-carriers, and no adverse psychological outcomes were observed amongst carriers.