This research aimed to find out the factors that affect tourists loyalty in the area of Toba Lake. This is a long-term developmental research that conducted in 3 (three) years in stages. This research was conducted at several tourist destinations in the tourist area of Toba Lake, in North Sumatera, namely Simalungun District, Toba Samosir District, Samosir District, North Tapanuli District, Humbang Hasundutan District, Karo District, and Dairi District. Data collection techniques used were observations, interviews, documentation studies, and questionnaires, whilst the factor analysis method was used in data analysis. The results of this research indicated that marketing mix factor is a dominant, affecting factor of tourists loyalty. The service quality and tourists satisfaction factor delivered a positive effect on tourists loyalty.
