Objective: Multiple psychotropic medications are routinely prescribed to treat bipolar disorder, creating complex medication regimens. This study investigated whether the daily number of psychotropic medications or the daily number of pills were associated with self-reported adherence with taking a mood stabilizer. Methods: Patients self-reported their mood and medications taken daily for about 6 months. Adherence was defined as taking at least one pill of any mood stabilizer daily. Univariate general linear models (GLMs) were used to estimate if adherence was associated with the number of daily medications and the number of pills, controlling for age. The association between mean daily dosage of mood stabilizer and adherence was also estimated using a GLM. Results: Three hundred and twelve patients (mean age 38.4±10.9 years) returned 58,106 days of data and took a mean of 3.1±1.6 psychotropic medications daily (7.0±4.2 pills). No significant association was found between either the daily number of medications or the daily number of pills and adherence. For most mood stabilizers, patients with lower adherence took a significantly smaller mean daily dosage. Conclusions: The number of concurrent psychotropic medications may not be associated with adherence in bipolar disorder. Patients with lower adherence may be taking smaller dosages of mood stabilizers.