The human scalp is susceptible to microbial build-up if not thoroughly and frequently washed with the appropriate cleansing agents such as shampoos. This study investigated the antimicrobial efficacy of a medicated shampoo that was formulated using a blend of anionic and non-ionic surfactants as cleansing agent and triclosan (5-chloro-2-(2,4-dichlorophenoxy) phenol as the antimicrobial agent. The medicated shampoo was designed to cleanse the scalp, condition the hair and also eliminate fungal and bacterial microbes which can cause scalp disorders and diseases. The shampoo was tested against three selected fungal species (Candida spp, Aspergillus spp, Malassezia globosa) and two bacterial species (Staphylococcus aureus and Escherichia coli) at dilution concentrations (%) of 90, 80, 70, 60, 50, 40, 30, 20 and 10. The results of the antimicrobial susceptibility tests revealed that the shampoo was highly effective against the three fungi at all concentrations but the higher concentrations (50-90% dilution) had slightly greater efficacy than the lower concentrations (10-40% dilution). E. coli showed susceptibility to the medicated shampoo at all concentrations. The shampoo formulation showed no activity against S. aureus at all dilutions (10-90%) as there was no zone of inhibition. The medicated shampoo is evidently effective against Malassezia globosa, the fungus that causes dandruff, Aspergillus spp, Candida spp as well as E. coli at all dilution levels. The shampoo also displayed excellent cleansing power, good foamability and conditioning attributes.