The study, sought to assess the effectiveness of marketing mix strategies on sales volumes for OTC drugs by research based MNCs in Kenya. Specific objectives were; to determine the influence of price on sales volume of OTC medicines for MNCs in Kenya, to determine the influence of place on sales volume of OTC medicines for MNCs in Kenya, to determine the influence of promotion on sales volume of OTC medicines for MNCs in Kenya and to determine the influence of product on sales volume of OTC medicines for MNCs in Kenya. Descriptive research design was used. The target population of this study was MNCs that have a representative office or operate through a distributor and additionally deal with OTC drugs in Kenya. The study used a census method, where all the 13 MNCs were selected for the study. Data was collected from primary sources by use of a structured questionnaire. Data was analyzed mainly by use of descriptive statistics. Inferential statistics were conducted to establish the relationship between the study variables. The study found that modifying pricing mix element by a single unit would lead to an increase in sales volume of OTC medicines for MNCs in Kenya. Modifying place mix element by a single unit would lead to an increase in sales volume of OTC medicines for MNCs in Kenya. Modifying promotion mix element by a single unit would lead to an increase in sales volume of OTC medicines for MNCs in Kenya. Modifying product mix element by a single unit would lead to an increase in sales volume of OTC medicines for multinational pharmaceutical companies.