Background: Incidence of cerebral metastasis is increasing among lung cancer patients. Many factors have been reported associated with increased risk of brain metastasis. The aim of this retrospective analysis is to investigate the predictive factors for the development of brain metastasis in lung cancer patients. Methods: We retrospectively analyzed histologically proven lung cancer patients radiologically diagnosed of having brain metastases who presented to Kasr Al-Eini Center for Oncology (NEMROCK) in the period from 2004 till 2010, with follow up period of 6 months at least. The following factors were analyzed: age, gender, PS, smoking history, tumor size & grade preceding development of brain metastasis. Results: Our study included 403 patients. 67 patients (16.6%) experienced brain metastasis during the course of their disease. 40 (10%) patients had brain metastasis among other sites of distant spread at first presentation which represent 88.9% of patients presented with metastatic disease. In a median follow-up of 17.1 months (6-77) the time to develop brain metastasis (TTBM) for the whole group was 5 months (range 2-22 months) (95% CI : 4.3-7.7). The most important factor affecting the TTBM was the use of chemotherapy before developing brain metastasis with a median TTBM of 5.9 months (95%CI : 3.2-6.8) among those who received chemotherapy compared to 2 months among the patients who didn't receive chemotherapy (P= <0.0001). The second factor was PS at time of initial diagnosis (P= 0.027). The median OS after brain metastasis was 6 months (95% CI : 4.26-7.74). On univariate analysis, PS and use of chemotherapy after developing brain metastases showed statistically significant difference affecting OS. Conclusions: We concluded that PS as well as use of chemotherapy are the 2 main factors associated with shorter time to develop brain metastasis. PS and use of chemotherapy after developing brain metastases showed longer OS after developing brain metastases.