This paper aims to determine the influence of contextual factors on information seeking behavior. This survey investigates search tactics used and users’ perceptions of the search results on the Web by postgraduate students at Kerman University of Medical Sciences. This study was conducted through a mixed method. Thirty postgraduate students voluntarily participated. The study was carried out in the first semester of the academic year 2012-2013. The data was gathered using two questionnaires and log files recorded with Camtasia Studio software. The findings indicated more than half of the participants (53.3 percent) used Google, short queries were more used than long queries, advanced search options were used rarely (23 percent), and the participants view few search result pages. According to the results, the contextual factors significantly influenced the search time, search tactics (including querying and navigating) and users’ perceptions of the search results (including ease of use, usefulness, satisfaction and relevance judgment). Navigating tactic was primarily used by the participants. Among different aspects of users’ perceptions of the search results, ease of use and relevance judgments were significantly different based on the contextual factors, whereas scanning, extracting, and confidence were less affected by the contextual factors. The findings suggest practical implications for information retrieval systems designers that can design of systems with better user interface in order to meet the needs of users with different knowledge and skills, in this way it leads in promotion of search process and improvement of search results quality.