Objectives: Despite the growing numbers and proportion of older adults with bipolar disorder (OABD), there are very limited guidelines for the use of lithium with its double-edged potential for effectiveness and toxicity in this population. The primary aims of this Delphi survey were: (a) To determine the place of lithium among the preferred choices for maintenance treatment of OABD. (b) To provide detailed clinical guidelines for the safe and effective use of lithium in OABD. Methods: In the face of limited evidence, the Delphi survey method was used to achieve consensus by a group of 25 experts in OABD from nine countries. An oversight committee monitored and analyzed the results of each survey and formulated more focused questions with each subsequent iteration. Results: A 100% response rate was achieved for all three iterations of the survey. Lithium was the preferred choice for maintenance monotherapy in OABD. Serum levels of 0.4-0.8 mmol/L were recommended for ages 60-79 and serum levels of 0.4-0.7 mmol/L were recommended for ages 80 and over. Specific recommendations achieved consensus for second line monotherapy as well as for other drugs to be used in combination with lithium if necessary. Guidelines for routine monitoring of lithium in OABD were provided for laboratory investigations and clinical assessments. Conclusions: Lithium remains the preferred choice for maintenance monotherapy in OABD. Laboratories should report the therapeutic range for serum levels of lithium separately for older adults.