This study compares the severity of unilateral and bilateral clubfoot, and the correlation between right and left feet of bilateral cases. Sixty-six unilateral and 75 bilateral clubfoot patients were assessed for severity using the Pirani score at an average age of 12.9 days (SD 9 days). In bilateral cases, the severity of right and left feet was highly correlated (r=0.68). The odds of being very severe were 2.6 (95% confidence interval 1.3–5.1) times higher in bilateral cases (P=0.007). Bilateral and unilateral clubfeet present with differing severity. Right and left feet from bilateral cases are highly correlated. Researchers need to address these issues during study design and analysis.