The most common malignant neoplasm in Childhood is Leukemia which is about 41% of all malignancies. Incidence of CNS involvement is less than 5% in Acute Lymphoblastic Leukemia and 6-29% in Acute Myeloblastic Leukemia at Diagnosis. For Successful treatment of childhood leukemia it is mandatory, to give sufficient therapy directed to the CNS to treat sub clinical or overt CNS Leukemia. Without Central Nervous System- Directed therapy, relapses originating from the CNS in up to 75% cases. For this purpose it is crucial to find out the CNS involvement in acute leukemia at diagnosis. This study was conducted to find proportion and pattern of central nervous system involvement (central nervous system manifestation and/or cerebrospinal fluid findings) in acute leukemia at diagnosis in Bangladesh. A cross sectional study was conducted from May 2012 to November 2012 in the Department of Pediatric Hematology and Oncology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh. Total 50 samples were included those having age <15 years newly diagnosed with acute leukemia by purposive sampling. Common age group 1-5 years (48%), 32 patients (64%) were male and 18 patients (36%) were female. Out of 32 male patients 4 patients presented with CNS manifestation and among 18 female patients 2 patients presented with CNS manifestation. There is no association between sex and CNS presentation (P value 0.89). 25 (50%) patients had total leukocyte count >11,000-1,00,000. Twelve (24%) patients had total leukocyte count <4,000. Eight (16%) patients had total leukocyte count 4,000-11,000, and rest 05(10%) patients had leukocyte count >1,00,000. Proportion of CNS manifestation was found 6/50 patients. Eight (8) patients were suffering from AML and 42 patients were suffering form ALL. Among 8 AML patients 1 (11.1%) patient had CNS manifestation and Among 42 ALL patients 5(11.1%) patients had CNS manifestation. Out of 6 patients with CNS manifestation, 2 (04%) patients presented with clinical manifestation, and 5(10%) had positive CSF findings. Pattern of CSF finding of 50 leukemic children CNS-1 90%, CNS-2 02%, CNS-3 08%, and no patients had traumatic lumber puncture with concomitant presence of blasts cells. There is significant association was found between hyper leukocytosis and CNS manifestation (p=0.138) but there is no statistically significant association between positive CSF findings and neurological findings (p=0.082). At conclusion, CNS manifestation is not uncommon (6/50 patients) was found in acute leukemia at diagnosis. So, every patient of acute leukemia should be examined carefully for CNS involvement along with CSF cytospin.