Background and objective: Due to nonadherence of tuberculosis (TB) patients to treatment, complications may arise and if remaining infectious, these patients may infect other people with TB. To obtain information about factors associated with nonadherence, we performed a study comparing adherent and nonadherent TB patients. Methods: Adherent and nonadherent patients randomly selected from hospital records in one urban and two rural districts were interviewed using semi-structured questionnaires. Key informant interviews were done with TB nurses and doctors. Results: The most frequently mentioned reason for nonadherence to treatment was feeling better. Although the drugs were given free of charge, many patients were nonadherent because of lack of money. Social support was considered very important for adherence. The study indicated that some patients had a negative image about the health care staff, treatment, and quality of medication. Conclusion: Treatment adherence of TB patients receiving treatment in hospitals in Central Java might be improved by providing health education about treatment duration and side effects, facilitating procedures for receiving treatment free of charge and reducing costs of transportation and consultation. Qualified friendly health care staff able to motivate patients might further improve adherence.