Fifty-one bipolar patients receiving maintenance lithium treatment were evaluated for the presence of side effects, their degree of distress, and the association of these side effects with compliance. Cognitive side effects and weight gain were the most disturbing to patients, whereas thirst and polyuria were the most common. Self-reported noncompliance correlated most highly with coordination (r = .38, p less than .01) and cognition (r = .30, p less than .05) side effects. Current depressed mood also showed a strong correlation with side effect scores, especially those for cognitive disturbances. However, the correlations between noncompliance and coordination and cognitive side effects were just as strong when the effects of depressed mood were partialled out. These findings indicate the link between noncompliance and lithium-induced central nervous side effects and suggest that related treatment issues must be addressed to ensure maximum clinical response.