Background: The growing trend of breast cancer in Iran and the adverse consequences arising from the delay in diagnosis and treatment in females has been a challenge. Objectives: This study was conducted to identify the predictors for diagnosis and treatment delay in females with breast cancer in the north of Iran. Methods: This cross-sectional study was performed on 232 patients with a definite diagnosis of breast cancer at Razi Hospital, which is the main referral centre in Guilan Province, Iran, using sequential sampling methods. Data were collected using a six-section questionnaire through interviews and medical records of the patients. Data were analyzed using descriptive statistics, logistic regression and chi square test. Results: Delays of more than one month was observed in 53% of patients and more than three months delay was observed in 31%. Of the patients with a definite diagnosis of breast cancer, 87% returned within seven days for treatment interventions. Three variables of: stage of disease (stage II: P = 0.002, OR = 7.19 and stage III: P = 0.034, OR = 1.95), lack of complementary insurance (P = 0.007, OR = 2.26) and primary insurance (P = 0.067, OR = 3.52) were important risk factors for patient delay. Knowledge and attitude regarding the symptoms of breast cancer (P = 0.007), the most important method for breast cancer diagnosis (P = 0.004), and the importance of self-examination was significantly different between patients with and without delay in the onset of treatment. Conclusions: This study showed that about one-third of patients with breast cancer had a patient delay of more than three months. In addition, 16.8% and 13% of patients experienced system delay in diagnosis and treatment, respectively. The government is responsible to not only teach people on the signs of breast cancer, but also to establish a powerful screening system for breast cancer.