Grazing livestock and equines are at risk of infection from a variety of helminths, for which the primary method of control has long been the use of anthelmintics. Anthelmintic resistance is now widespread in a number of helminth species across the globe so it is imperative that best practice control principles be adopted to delay the further spread of resistance. It is the responsibility of all who prescribe anthelmintics (in the UK, this being veterinarians, suitably qualified persons (SQPs) and pharmacists) to provide adequate information on best practice approaches to parasite control at the point of purchase. Poor uptake of best practice guidelines at farm level has been documented; this could be due to a lack of, or inappropriate, advice at the point of anthelmintics purchase. Therefore, the aim here was to evaluate levels of basic knowledge of helminthology, best practice guidelines and dispensing legislation among veterinarians and SQPs in the UK, through a Multiple Choice Question (MCQ) test, that was distributed online via targeted emails and social media sites. For each respondent, the percentage correct was determined (for the MCQ test overall and for subsections) and the results analysed initially using parametric and non-parametric statistics to compare differences between prescribing channels. The results showed that channels generally performed well; veterinarians achieved a mean total percentage correct of 79.7% (range 34.0-100%) and SQPs, a mean total percentage correct of 75.8% (range 38.5-100%) (p = 0.051). The analysis indicated that veterinarians performed better in terms of knowledge of basic helminthology (p = 0.001), whilst the SQP group performed better on legislation type questions (p = 0.032). There was no significant difference in knowledge levels of best practice between the two channels. Multivariable linear regression analysis showed that veterinarians and those answering equine questions only performed significantly better than those answering all questions. Based on information gaps identified by analysis of individual questions, a number of areas for improvement in knowledge transfer to both channels are suggested to improve the quality of advice at the point of anthelmintics purchase.