The atomic transition probabilities for individual and multiplet lines of lithium atom are obtained using weakest bound electron potential model theory (WBEPMT) and exact quantum defect theory. The results obtained using two different methods agree very well with the accepted values taken from NIST, MCHF results and Opacity Project values. These methods require substantially less computational time than well-known theoretical methods, thereby permitting the study of 108 transitions. © 2006 Elsevier Ltd. All rights reserved.