OBJECTIVES: Achieving optimal patient adherence to IV medication is a major challenge in clinical management of chronic diseases. The objectives of this literature review were to identify the factors that influence patient non-adherence to IV medication for chronic conditions and evaluate if an optimum relationship between dosing frequency and adherence exists. METHODS: A database search for adherence to IV medication was conducted through Medline, Embase and Biosis databases. Inclusion and exclusion criteria were applied before each published article or abstract (1990-May 2012) was appraised. Primary research studies, in English language, with an analysis of adherence rates and or factors in a chronic condition were included. RESULTS: Twelve primary studies were identified and reviewed across two chronic conditions: osteoporosis (8) and Crohn’s Disease (4). Multiple patient-related and therapy-related factors were reported to influence non-adherence to IV medication.  The most frequently identified factors influencing non-adherence were therapy-related: poor tolerability and side effects (3 studies) and inconvenience of location for therapy (3 studies). In two studies comparing directly IV dosing frequency in osteoporosis therapy, adherence was greater for annual therapy vs every 3 months (82% vs 58-62% and 65.6% vs 56.6% respectively). There was a wide range in the reported rate of non-adherence across studies in both osteoporosis and Crohn’s Disease (17.1% to 43.4% and 27% to 40%, respectively). A threshold for IV dosing frequency that optimises adherence could not clearly be assessed. CONCLUSIONS: Dosing frequency appears to be one determinant of non-adherence among chronic diseases along with multiple other factors, most notably tolerability and convenience.  Further primary research is required to determine the relative influence of IV dosing frequency and other therapy-related factors in management of specific chronic diseases in clinical practice.