PURPOSE: THE PURPOSE OF PRESENT RESEARCH WAS TO IDENTIFY THE FACTORS AFFECTING ON Fans' BEHAVIOR IMPROVEMENT IN IRAN HANDBALL PREMIER LEAGUE COMPETITION.METHODOLOGY: THE RESEARCH METHOD WAS DESCRIPTIVE - SURVEY. THE STATISTICAL POPULATION WAS COMPOSED OF PRESENT Fans IN IRAN HANDBALL PREMIER LEAGUE COMPETITIONS. FINALLY, 358 Fans WHO WERE MEN AND WOMEN RANDOMLY SELECTED AS THE SAMPLE. RESEARCHER- MADE QUESTIONNAIRE WAS USED TO COLLECT DATA WHICH ITS CONTENT AND FACE VALIDITY WAS CHECKED AND CONFIRMED BY A GROUP OF EXPERTS.CRONBACH'S ALPHA COEFFICIENT WAS USED TO TEST THE RELIABILITY OF THE QUESTIONNA IRE (A=0.92). THE RESPONDENTS WERE ASKED TO INDICATE THEIR AGREEMENT ON A LIKERT SCALE RANGING FROM 1 (STRONGLY DISAGREE) TO 5 (STRONGLY AGREE). DATA WERE ANALYZED WITH USING DESCRIPTIVE AND INFERENTIAL STATISTICAL TESTS (FACTOR ANALYSIS, KOLMOGOROV-SMIRNOV, MANN-WHITNEY U). ACCORDING TO FACTOR ANALYSIS, 38 VARIABLES WERE CLASSIFIED INTO SIX CATEGORIES “ENVIRONMENTAL, CULTURAL, SECURITY, PROTECTIVE, PSYCHOLOGICAL AND MANAGERIAL”.RESULTS: ALSO THE RESULTS SHOWED THAT THERE WERE NO SIGNIFICANT DIFFERENCES AMONG ENVIRONMENTAL, CULTURAL, PSYCHOLOGICAL AND MANAGERIAL FACTORS BETWEEN MALE AND FEMALE Fans (P>0.05). ON THE OTHER HAND, THERE WERE SIGNIFICANT DIFFERENCES BETWEEN SECURITY AND PROTECTIVE FACTORS BETWEEN THESE TWO GROUPS (P<0.05). ACCORDING TO THE RESULTS, ATTENTION TO SIX FACTORS LISTED, IN PARTICULAR, SECURITY AND PROTECTIVE FACTORS COULD BE A MAJOR STEP IN IMPROVING BEHAVIOR OF Fans.